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"You cannot fathom the mysteries of the Universe, you must simply trust in the righteousness of the Emperor's Command."

—Edicts of the Navigator Guild Calixis
The Warhammer 40k Galaxy Map

The Milky Way Galaxy in the 41st Millennium AD before the creation of the Great Rift.

The Imperium of Man is home to over 1,000,000 Human-settled planets scattered across over 100,000 light years of space in the Milky Way Galaxy. Most of these worlds were settled by Humans many centuries before the Great Crusade of the 30th and 31st Millenniums reunited the Human colony planets beneath the rulership of the Emperor of Mankind, though thousands more have been settled in the ten millennia since by Imperial colonists.

The Imperium of Man is spread impossibly thin across an estimated two-thirds of the entire Milky Way Galaxy. The volume of space claimed in the name of the Emperor of Mankind contains hundreds of millions of stars, many host to their own planetary systems, and yet there are only an estimated million or so planetary governors occupying the thrones of the Imperium’s worlds.


The Milky Way Galaxy after the formation of the Great Rift in the Era Indomitus.

While it is true that some governors rule not just a single planet but an entire star system, and that other worlds have no governor at all, the fact is that the Imperium is stretched so thinly across the void that an interstellar traveller could make their way from one edge to the other, traversing a hundred thousand light years of space, and not once cross paths with another Human being.

Instead of being scattered at random, the worlds of the Imperium are clustered around areas settled during the lost age of Mankind's first great wave of expansion into the galaxy during the Age of Technology. Worlds once colonised because of their location or some desirable natural resource have developed into the cores of sectors, many of which have swollen to include two hundred or more star systems.


The galaxy in the Era Indomitus in the wake of the birth of the Great Rift.

These sectors are connected to one another by relatively stable, if still hazardous, inter-sector Warp routes and the vast, uncharted reaches between each are referred to as Wilderness Space. These unexplored depths harbour all manner of terrors, from ravening pirates to unknown alien empires, as well as untold riches, from long-lost Human colonies to worlds strewn with the wealth of long-extinct xenos species.

The Imperium encompasses countless worlds. No one has ever been able to map all of them and no one can truly even say how many there are beyond the figure of 1,000,000 normally cited above. Entire departments of the Adeptus Administratum are devoted to cataloguing the worlds in the Emperor's domains, a never-ending task, for it is in a state of eternal flux. Furthermore, the Adeptus Terra holds that the whole Human race and the entire galaxy are under the Emperor's rule -- the Imperium has a Manifest Destiny to unite Humanity, impose its laws on every Human world and destroy all alien forms of intelligent life.

The true scope of the Imperium is, therefore, the entire galaxy, though this is far from actuality. The Imperium jealously guards its territory wherever it can but its sheer size means that it cannot react to every circumstance.

Many planets live and die alone, with only the truly great threats commanding the attention of the Adeptus Terra. Worlds are frequently lost to aliens, rebellion or disasters, with news of their destruction sometimes taking centuries to reach Terra. The Imperium’s borders undergo constant change, with new worlds discovered, conquered or colonised and old ones lost to xenos invasion, Exterminatus, daemonic incursion or even to the Warp itself.

Types of Planets

The galaxy teems with worlds. The majority are gas giants, worlds of frozen methane, huge, globular masses of hydrogen that failed to become stars, and many other variations.

Some of these are mined or exploited in some way and may even harbour their own forms of truly bizarre alien life, but it is mostly upon small, rocky, terrestrial worlds that Mankind, and its enemies, are found. Within this category of world, however, are many variations and Humanity endures all manner of different environments in its quest to survive in a cruel and unwelcoming universe.

The Adeptus Administratum of the Imperium generally classifies all planets in the galaxy according to the following classifications for the purposes of raising tithes of raw materials, manufactured products and Astra Militarum regiments.

Feudal Worlds

Feudal Worlds are planets into which the Imperium has not seen fit to introduce most modern technology, although the advent of certain advanced medical technologies such as basic antiseptic agents is often an exception so as to keep such worlds' labour productivity high in the face of the odd plague or epidemic.

Feudal Worlds are defined as those planets of the Imperium that have developed late Iron Age civilisations that are moderately technologically advanced while still remaining pre-industrial, having usually progressed as far as to discover or re-discover rudimentary gunpowder weapons. These planets often possess widespread and advanced agricultural economies and typically have a population of 10,000,000 to 500,000,000 people. Feudal Worlds are similar culturally and technologically to Terran societies in the Late Middle Ages or Renaissance periods of the Age of Progress.

Generally, Feudal Worlds will have little direct political or economic interference from the Imperium and be required to pay only low planetary tithes. Imperial planetary governors of Feudal Worlds will generally live on a space station in orbit of the planet to avoid altering the cultural balance, only descending to the surface to deal with heresy, rebellion or rampant mutation.

These planets are populated by folk who have lost access to all but the most basic of technologies and maintain Iron Age or early Gunpowder Age societies. Farming, simple labour-intensive machines such as pulleys, windmills and the like are known, but propelled flight, automatic weaponry and powered vehicles are likely to be rare or non-existent. These worlds are often said to be the most politically harmonious of all the planets of the Imperium, because their peoples know their place.

For examples see: Fervious, Sisk

Feral Worlds

Feral Worlds are defined as planets whose population are composed of nomadic hunter-gatherers or members of early agricultural societies and who possess technology equivalent to Old Earth's Stone Age, Bronze Age or early Iron Age cultures. Feral Worlds are populated by tribal peoples largely living without the assistance of maintained technology or even agriculture in some cases and the population is usually quite low as a result, ranging from 100,000 to 5,000,000 people. This may be due to an ancient failed Human colonisation project from the Age of Technology, ingrained religious preferences, cultural choice, harshness of the environment or some other reason.

Feral Worlds, like their Feudal counterparts, will have little direct political or economic interference from the Imperium and will pay only the lowest grades of planetary tithes, their tithe grade being Solutio Tertius. Feral World populations may be aware of the Imperium's existence in some fashion but are unlikely to know much more than something about a large group of distant people living among the stars.

These planets are frequently unsuitable for later Imperial colonisation, either due to the circumstances which drove the natives feral or because the natives themselves actively resist new people settling on their lands. The people of Feral Worlds can range widely in culture, from Grox-hunting Stone Age tribes of ancestor worshipers who only recognize the Emperor of Mankind in the most rudimentary of ways, to wild-eyed, post-apocalyptic road warriors, fighting endlessly amongst the toxic, sand-strewn ruins of their civilisation.

The harsh conditions which Feral World populations have adapted to makes them ideal recruitment sources for the regiments of the Astra Militarum and the Chapters of the Space Marines since they produce more men with experience in war. Occasionally the inhabitants of Feral Worlds have been pressed into the service of the Astra Militarum when their world lay inside a war zone, and the chosen warriors have been given rudimentary training in the operation of laser or stub-weaponry. It is more common, however, for Feral World natives to be selected for the various Adeptus Astartes recruitment programs.

Like all Imperial worlds, Feral Worlds are ruled over by a planetary governor, although the nature of Feral Worlds makes this position somewhat different from that of the governorship of more advanced planets. The Imperial governor of a Feral World almost always lives apart from the natives, often living in a single city inhabited by outsiders or taking residence in orbit on an Imperial space station, only interfering in the world's affairs to keep psyker and mutant "head counts" down. Religious heresy is also a regular concern on Feral Worlds, especially amongst warrior-cults prone to infiltration by agents of Khorne, the Blood God; constant vigilance and regular belief-modification enacted by agents of the Ecclesiarchy are a necessity.

Governors and permanent staff on such worlds are themselves kept under close scrutiny, in an effort to avoid the phenomenon of "going native," especially in situations where the inhabitants' belief systems have been manipulated into casting the governor as a "star god."

The culture shock associated with interaction with more technologically advanced outsiders is an issue on Feral Worlds. Removing a Feral Worlder from their planet and exposing them to such things as Warp travel can be disconcerting and even result in madness and other permanent psychological disorders. A Feral Worlder within the wider Imperium often retains their superstitious and tribal idiosyncrasies, which may prove to be social hindrances, such as an obsession with the bones of dead comrades or the mixing and regular application of noxious-smelling warpaint. Other habits, such as manic distrust and aversion to psychic "witchcraft" may be seen as useful and sensible in the wider society of the Imperium.

For examples see: Dusk, Fedrid, Volonx

Forge Worlds

Forge World Smog

A Forge World of the Adeptus Mechanicus

Forge World is an Imperial term for the numerous planets that are directly controlled by the Adeptus Mechanicus. All have in common that they are completely dedicated to the manufacture of the various machines, advanced technology and other devices of the Imperium, the pursuit of and preservation of (ancient) scientific and technical knowledge and the worship of the deity called the Machine God.

Because of the Adeptus Mechanicus' monopoly on technical knowledge and scientific expertise in Imperial culture, the Forge Worlds are the Imperium's primary source of all kinds of hardware: from farming equipment to war machines such as starships, tanks, aerospace fighters, or even Imperial Titans. Ancient pacts between the Adeptus Mechanicus and other worlds and institutions of the Imperium oblige the various Forge Worlds to supply other planets and the various military arms of the Imperium such as the Astra Militarum and the Adeptus Astartes with the products of their manufactoria.

Much of a Forge World is like an immense factory, with industrial complexes soaring into the sky and mine workings burrowing deep into the planetary crust. Forge Worlds build great numbers of complex technologies, like main battle tanks or spacecraft parts for the Astra Militarum and the Navis Imperialis. They are ruled by the Adeptus Mechanicus, whose training and research facilities are located there, along with the grand cathedrals to their deity, the Omnissiah, in which the ruling archmagi of the Tech-priests enact the grandest, most complex rituals to honor the Machine God.

The Adeptus Mechanicus' fleets, its armies of cybernetically-enhanced Tech-Guard warriors and, most formidably of all, the Titan Legions, are also all based on Forge Worlds. The Forge Worlds are largely politically autonomous from the rest of the Imperium, as allowed by the terms of the Treaty of Mars that founded the Imperium in the 30th Millennium, and the Adeptus Mechanicus is loath to allow anyone on their surface other than Tech-priests and the legions of menial, cybernetic servitors who labour for them.

Forge World Inside Factory

View from the inside of a Leman Russ Tank factory.

The surface of a Forge World is normally completely covered in massive factory complexes called "manufactoria" that stretch across the horizon. Its ecosystem has been completely destroyed. The air is saturated with toxic gases and rivers flow with toxic runoff from the multitude of manufactoria. In many cases, even seas and oceans have been purposefully evaporated to make room for more manufactoria.

However, the sheer amount of industrial output greatly benefits the Imperium as a whole. All of the items produced by a Forge World are constructed according to a very specific design formula that varies from Forge World to Forge World, even for otherwise identical pieces of the same equipment and these variant designs are known as that Forge World's "pattern."

While there are hundreds of Forge Worlds in the Imperium, the most important is Mars, home of the Adeptus Mechanicus' political and spiritual head, the fabricator-general of Mars; and the Imperium's first Forge World. Other Forge Worlds include Ryza, known for its advanced plasma technology; Gryphonne IV, home of the Titan Legio Gryphonicus; Agripinaa, a primary supplier of military goods to the former Fortress World of Cadia; Phaeton, manufacturer of the Leman Russ main battle tank; and Urdesh, the primary Forge World within the Sabbat Worlds Sector.

Of all the Forge Worlds only Trebor caters exclusively to the industrial needs of Cadia. One of the most sought-after creations from Trebor is its version of the Vanquisher Cannon, which is the most powerful of all the Vanquisher Cannon variants. During the Age of Technology, the twin empires of Terra and Mars co-existed, to the mutual benefit of both. Trebor was colonised from survivors of colony expeditions from both Terra and Mars after they were lost during a Warp Storm. This forced both colonies to combine their knowledge and build the most technologically-advanced of all the Forge Worlds.

Trebor was only re-discovered by Commissar Yarrick during the Second War for Armageddon in the 41st Millennium. As a result, Trebor has sworn its allegiance only to Commissar Yarrick and to Cadia, and its arms and technology made a major difference in the valiant but unsuccessful defence of Cadia during the 13th Black Crusade.

For examples see: Mars, The Lathes, Belacane and Fortis Binary

Armoury Worlds

An Armoury World is the Imperial term for a planet that is used by the Departmento Munitorum to store vast amounts of weapons, ammunition, and war machines. These heavily defended worlds are the places where weapons, vehicles, ammunition, and other military equipment are stored while they await to be transported to wherever they are needed.

An Armoury World could have thousands of armoured vehicles of every type and millions of tonnes of munitions and other materiel stored in its vast storehouses for hundreds or even thousands of standard years until the Imperium had need of them. Some Armoury Worlds store vehicles, weapons, and other equipment that are so old that the secrets of their manufacture have been nearly lost by the Adeptus Mechanicus, such as the ancient Imperial heavy tank known as the Valdor Tank Hunter.

For examples see: Vraks Prime

Hive Worlds

The Imperium's most populous worlds are its Hive Worlds, of which there are approximately 32,380 in the Imperium. The populations of these planets are so great that the people live in huge urban arcologies called hive cities, truly immense, self-contained, many-layered structures that reach high into the sky, each housing billions of individuals.

Hive Worlds often provide much-needed industrial labour, their manufactoria producing mountains of war materiel and other goods to meet the Imperial tithe's demands. Most Hive Worlds started out as relatively hospitable places to live but have become severely polluted, the regions outside the hives reduced to ash wastes or radioactive desert by the never-ceasing industry of the great cities.

Equally dangerous can be the hives themselves. The crime-ridden, poverty-stricken areas, almost always found in the most polluted and decrepit lower levels of the under-hive, are home to violent gangs, criminals and assorted scum as well as mutants and heretical cults who hide there from the authorities. It has been said that the sacrifice of over a million Imperial soldiers is worth "one day's Hive World production" in weapons and armour.

Perhaps even more valuable is what at first glance seems to be a byproduct of the monolithic hive city's design. The population of any given world approximately doubles every 100 standard years. With each hive housing between 10 to 100 billion people and 5 to 20 hives per planet, the sheer number of Imperial citizens on a Hive World is staggering. And each of those citizens is a potential soldier for the Emperor's already uncountably vast armies.

Hive cities manufacture far more than mere steel and silica; they are vast factories for the most useful possible resource, people. Almost every recruit into the Astra Militarum from a Hive World will already know how to handle a weapon. Hive Worlds also serve to populate newly discovered planets. Imperial citizens are gathered from various Hive Worlds (willingly or unwillingly) by the Administratum and shipped off to distant colonies first discovered by the Adeptus Mechanicus' Explorator fleets.

In common with most other Imperial worlds, Hive Worlds are often based on a very obvious socioeconomic class system, with a ruling noble class and a bureaucratic middle class, although with populations so tightly packed there always develops a lower working class that often fuels violent street gangs. As can be expected, the upper classes are situated in the affluent upper areas of the hive cities, whilst the middle classes are situated in the middle areas, and the working classes are packed together in the lower areas. The very bottom sections of a hive city, the "underhive," are often areas where the underclasses and criminals are sent to be forgotten about and anarchy rules.

Some extensively developed Hive Worlds do not even consist of various enclosed arcologies surrounded by wasteland, jungle, ice, or plains. These Hive Worlds are completely urbanised and stacked with hundreds of layers of arcologies, covering the entirety of the planet, effectively becoming an ecumenopolis. Terra is an example of this type of "Super Hive World."

For examples see: Scintilla, Barsapine, Fenksworld, Malfi, Prol IX, Tranch, Vaxanide, Medusa V, Armageddon, Terra (where the whole planet is one hive city), Necromunda and Verghast.

Knight Worlds

The Knight Worlds are Human-settled, technologically-advanced planets within the Imperium of Man that are home to the powerful, robotic combat walkers known as Imperial Knights. Knight Worlds are allied with both the Imperium directly and are also sometimes part of the demesne of the Adeptus Mechanicus.

They almost universally maintain feudal cultures and social structures reminiscent of the Terran Middle Ages during the early 2nd Millennium AD. These planets are descended from venerable Human colonies first settled during the Age of Technology.

Ancient oaths of fealty mean that the Imperial Knights that call these worlds home, and for which they are named, are sworn to protect their citizens. These oaths also require that the Knights fight against the Imperium's and sometimes the Mechanicus' enemies when called upon to do so. The Knight Worlds are ruled by feudal "Noble" houses called Knight Houses because their members are trained to pilot the massive humanoid war machines that are the Imperial Knights.

Many Knight Worlds are politically and economically linked with a nearby Mechanicus Forge World and their Knights are considered to be a part of what is known in High Gothic as the "Questor Mechanicus." Others remain completely independent of the Tech-priests' ambitions and serve the Imperium directly, their Nobles members of the so-called "Questor Imperialis."

There are many hundreds of Knight Worlds scattered throughout the vast empire of Mankind. The bold explorers of Humanity's first interstellar expansion during the Age of Technology travelled far and wide into the galactic wilderness seeking habitable worlds or planets that could otherwise be terraformed to sustain Human life. Many of these exploratory fleets were equipped with Standard Template Construct (STC) technology that included the schematics for the Knight, enabling them to protect the colonies they established.

More than fifteen standard millennia after their ancient ancestors set out into the stars, the distant descendants of these Human colonists dwell still on Knight Worlds scattered across the demesne of the Imperium. Though many knightly houses have risen and fallen over the ages, those that remain can trace their heritage back to a time before the birth of the Imperium, and are justifiably proud of their ancestry. Thus is every Knight World heavy with the weight of the past, regardless of its galactic location or level of technological advancement.

For examples see: Adrastapol, Alaric Prime

Shrine Worlds

Shrine Worlds are dominated by the religion of the Imperial Cult and acts of devotion to the God-Emperor of Mankind. It may be that these places saw the birth of a famous Imperial saint or formed the battleground for a particularly important war in the Imperium's history. Often studded with cathedrals, temples and shrines spread across the globe to the Emperor and His saints, these worlds are frequently directly controlled by the Ecclesiarchy and may form training grounds for members of the Adeptus Ministorum and the Adepta Sororitas.

There are also dark mirrors to these places of Imperial devotion -- fallen worlds outside the grace of the Emperor where the heretical Chaos Cultist inhabitants offer up ceaseless prayers to the Ruinous Powers of Chaos. These places of obscene sacrifices and bloody rites are not suffered continued existence for long by the Imperium if they exist within realspace.

A Shrine World can also be considered to belong to another category of world at the same time, as for example Hagia is also classified as an Agri-world while Herodor is also a Hive World. All Shrine Worlds will have a strong relationship with the Imperial saint connected to the planet in question, such as being the world of their birth or death or the site of a major miracle the saint was responsible for performing in the name of the Emperor.

For examples see: Drusus Shrine World, Hagia and Herodor

Cardinal Worlds

Cardinal Worlds are Imperial planets ruled directly by the Ecclesiarchy and are completely dedicated to the worship of the God-Emperor according to the tenets of the Imperial Cult, with Imperial sanctuaries, cathedrals and temples potentially covering entire continents.

Aside from also being a Shrine World that is a particularly important centre of the Ecclesiarchy's power and a destination for the countless pilgrims of the Imperial Cult, they also serve as a base of operations for many orders of the Adepta Sororitas.

One example of an important Cardinal World is Ophelia VII, whose spiritual significance to the Imperial Cult is second only to that of Terra. The planetary governor is always a cardinal of the Adeptus Ministorum, who often leads the Ecclesiarchy's hierarchy in an entire sector of Imperial space.

For example see: Ophelia VII

Cemetery Worlds

Somewhat akin to Shrine Worlds are the Imperium's Cemetery Worlds, where large areas of the planet's surface have been given over to care for the remains of the honoured Imperial dead.

Cemetery Worlds may mark the site of a massive battle, or they may be covered in gigantic mausoleums, each dedicated to a particular Imperial noble family. In contrast some rare Cemetery Worlds may be covered in fields of endless, modest burial plots containing the remains of the inhabitants of a nearby Hive World.

For examples see: Certus Minor, Cryptus

Pleasure Worlds

Also known as Paradise Worlds and sometimes as Garden Worlds, Pleasure Worlds are the playgrounds of the Imperial nobility. They tend to be of outstanding natural beauty and the population of such worlds are dedicated to pampering the important Imperial visitors they often receive, such as members of major noble houses, members of the Navis Nobilite, planetary governors, important Ecclesiarchy officials like confessors and cardinals, Imperial military commanders, Rogue Traders and wealthy Chartist Captains.

Pleasure Worlds are often very cultured places, and many have huge proportions of their populace dedicated solely to producing works of art, music or other forms of entertainment. Casino complexes, opulent restaurants and huge ballrooms are often found on such worlds.

There is a darker side to Pleasure Worlds, particularly those who cater to the tastes of the more depraved guests they receive and Pleasure Worlds often host one or more Chaos Cults dedicated to Slaanesh, the Prince of Pleasure. Some Pleasure Worlds contain large developing cities and other major settlements. All Pleasure Worlds are considered a sub-set of the class of planets known as Civilised Worlds.

For examples see: Reth, Forraliss

War Worlds

There are a great many worlds in the Imperium that can be classed as war zones and they are called War Worlds. The Imperium is constantly at war and during those conflicts whole planets can burn. Massive Imperial military campaigns and Imperial Crusades can envelop dozens of star systems and hundreds of worlds, many of which are utterly devastated by orbital bombardments and artillery in planet-spanning battles that last for entire solar decades.

Long-term war zones are hellish places where death comes quickly. The Imperium can field truly immense armies of millions of troops, grinding their way across a devastated planet and reducing its cities to rubble. Mercenaries flock to such places, hoping to leave soon after with their ships loaded with pay and loot. Deserters and escaped prisoners form bands of pirates, preying on any starships unable to defend themselves. Or these reavers roam the war-torn planets in feral packs, stealing and killing anything that is not nailed down and anyone who gets in their way.

The Administratum sends colonists from more overcrowded worlds (sometimes willingly, sometimes not) to re-populate such war-torn worlds after the fighting has ended. But the bureaucratic wheels of the Imperium grind slowly and a world can lie devastated for standard centuries before any effort is made to resettle it. These places can be some of the most ghastly in the Imperium, with ravaged environments, cracked planetary crusts, burnt-out cities and plains covered in the rotting flesh of the fallen.

For examples see: Rynn's World, Sabbat Worlds, Malice

Fortress Worlds

Fortress Worlds are planets within the Imperium of Man that serve as bastions of the Imperium's defence against some constant and persistent threat to Imperial space. These worlds are extremely well-defended, usually with large numbers of Astra Militarum regiments and Imperial Navy assets, and their populations and economies are wholly geared towards meeting the demands of Imperial defence.

Unfortunately, not all Fortress Worlds are controlled by the Imperium, as several have fallen to the control of the Traitor Legions. The most famous Fortress World in the Imperium was Cadia, which defended the Cadian Gate, the only stable passage through the Warp from the Eye of Terror into open Imperial space, from the constant assaults of the forces of Chaos and Abaddon the Despoiler's Black Crusades. While Cadia has been lost to the Imperium following the success of the 13th Black Crusade, other worlds in the Cadian Gate have now stepped forwards to serve as a new line of fallback defence against the servants of the Dark Gods.

For examples see: Cadia, Jago, Medrengard

Sentinel Worlds

A Sentinel World, also sometimes called a Bastion World, is an Imperial planet that has been designated in the Era Indomitus to serve as an inviolable bulwark of the Emperor of Mankind's order within the region of the galaxy known as the Imperium Nihilus. Sentinel Worlds are expected to defend themselves against all the horrors assaulting the Dark Imperium beyond their aegis since it was cut off from the rest of the Emperor's realm with the birth of the Great Rift.

The Imperial planetological designation of Sentinel World is a new one created on the order of the Lord Commander of the Imperium Roboute Guilliman after his resurrection.

For examples see: Vigilus

Dead Worlds

Dead Worlds have minimal, even non-existent, life traces or biospheres. A Dead World often possesses a toxic atmosphere or none at all, its surface exposed to the vacuum of the open void. This results from ecological catastrophe, devastating internecine war with weapons of mass destruction, Imperial or alien intervention or can be due to no known attributable cause.

Dead Worlds often occur naturally, as the unforgiving conditions of the universe mean the majority of planets in the galaxy are uninhabitable. Some, however, have been created in the long history of the Imperium by catastrophic events, including an Exterminatus order or a successful Tyranid invasion.

Ironically, some planets classified as Dead Worlds have been settled by various groups specifically for their barren properties. For example, several Space Marine fortress-monasteries are located on Dead Worlds because of their harsh conditions, desolation and defensive opportunities.

Many Dead Worlds are also Necron Tomb Worlds, having suffered from one of the Necrons' devastating "red harvests" many millions of years ago which made all life on the planet extinct before the Necrons entered their stasis tombs deep below the barren world's crust.

For examples see: Belis Corona, Isstvan III

Derelict Worlds

Derelict Worlds are formerly Human or xenos-settled worlds of the galaxy that have been scoured by war or disaster and have not been seized by one of the major galactic powers. In time, the locations of many are simply lost to the void of Wilderness Space.

For examples see: Bairsten Prime

Rad Worlds

Rad Worlds also called a "Rad-soaked planet," is the Imperial planetological term for a planet that has been rendered virtually uninhabitable by Humans due to the presence of a high background level of deadly ionising radiation. The cause of this radiation may be the result of the prior use of radiogenic weapons of mass destruction such as nucleonic weapons or due to some natural environmental feature such as high levels of radiation given off by the world's star or an atmospheric deficiency such as the lack of an ozone layer.

Yet, despite this deadly danger, there are still Rad Worlds that have been inhabited by Imperial citizens and from which regiments of the Astra Militarum have been raised.

Tomb Worlds

A Tomb World is one of the worlds across the Milky Way Galaxy where the ancient and terrible xenos known as the Necrons chose to go into hibernation over 60 million standard years ago during the Great Sleep, deep beneath its surface in their specially prepared catacombs and tombs. Many Tomb Worlds are now settled planets of the Imperium of Man and their status as a Necron Tomb World remains unknown until the Necrons beneath its surface begin to awaken, much to the detriment of all life on the world.

An unknown number of these planets exist across the galaxy in the 41st Millennium. Some Tomb Worlds were once the settled worlds of the ancient Necrontyr species that eventually became the cybernetic Necrons after their enslavement by the C'tan, and Necrontyr ruins are sometimes found on or beneath the surfaces of such worlds. Many Necron Tomb Worlds are now Dead Worlds, largely lifeless and barren deserts. Whether this is a result of the Necrons having cleansed all life from the world millions of Terran years before during one of their foul "red harvests" or whether such climates were the preferred homeworlds of the Necrontyr civilisation, is unknown.

Many of these worlds are often the sites of archeological expeditions carried out by Adeptus Mechanicus Explorator teams looking to uncover ancient xenos or STC technologies or Rogue Trader expeditions hoping to turn a profit from what they discover. Many of these exploratory teams are never heard from again once they begin to explore Necrontyr ruins that inevitably lead them to the tombs of the dormant Necrons that lie beneath the sands.

The Necrons' underground stasis tombs are generally quite large and cavernous, containing repair facilities that are manned by Canoptek Spyder robots that repair the Necrons that were critically damaged in recent battles. They have stasis units, in which the dormant Necrons hibernate. They also usually have a large room in which either the Necron Lord or Necron Overlord that commands the Tomb World sleeps in a massive, ornate, black stone sarcophagus.

For examples see: Klybo, Lorn V, Kronus


Many planets in the Imperium, such as Forge Worlds and Hive Worlds, are completely incapable of sustaining the sheer number of people who live and work on them. To feed these people, as well as the vast armies of the Astra Militarum, many planets have been completely transformed into giant farms known as Agri-worlds. Most of these planets have populations of less than 100 million people and possess only a few major cities.

These farming planets, in their own way, are as vital to the Imperium as its hive cities. These planets are given over entirely to the production of food, which Hive Worlds cannot produce in sufficient quantities to keep their huge populations from starving. Many a world has whole continents given over to livestock or fields of crops.

Some Agri-worlds are covered in oceans teeming with fish and a few are far stranger -- worlds covered in edible fungus, scoured by swarms of nutritious insects or are gas giants whose upper atmospheric layers are home to flocks of edible or egg-producing flying creatures.

A few planets are used solely to provide clean, potable water to nearby Hive Worlds. Agri-worlds are sometimes ruled directly by the Adeptus Administratum rather than by their own local planetary government, to help ensure that their produce is grown and harvested with maximum efficiency.

For examples see: Iocanthus, Dreah, Orbel Quill, Siculi, and Spectoris

Arboreal Worlds

An Arboreal World is an Imperial planetological classification for a Human-settled planet where the majority of the population live in trees. Such worlds are rarely technologically advanced and their inhabitants may have some genetic adaptations to their arboreal lifestyle.

For examples see: Thoresta

Civilised Worlds

A Civilised World, also called a "Developing World," is a planet whose development has been allowed to progress over the millennia "naturally," without any specific purpose to fulfill. These worlds are generally self-sufficient in terms of food-supply and have varying manufacturing, technological and industrial capabilities. Civilised Worlds are split into geographical areas with widely varying levels of technological advancement and culture. Depending on the prevailing governments, these might be countries, states, power blocks or tribal homelands. It may be the case that higher levels of technology and wealth are concentrated around the original Human colonisation sites.

Other planets in this class might exhibit gross variations in culture due to environment, with areas weak in natural resources being similarly weak in terms of military power, economic muscle and so on. Some planets preserve a great divide due to ancient tribal taboos, religious notions or plain old-fashioned habit. A great many worlds of the Imperium of Man fit into this broad category, but no two are alike in the way they realise these developmental divides.

By the Imperial planetological classification guidelines, a Civilised World is one that has a population from 15,000,000 all the way up to 10,000,000,000 people and pays moderately high Imperial tithes. It may have large, sprawling urban areas but none have yet reached the level of population density or self-sufficiency to be considered a true hive city. Many Civilised Worlds may be equivalent in culture and population levels to Old Earth during the Age of Progress in the early 3rd Millennium.

For examples see: Gudrun, Volistad, Kronus

Space Marine Chapter Homeworlds

A Space Marine Chapter Homeworld is an Imperial planetological classification for a world that serves as a base for a Space Marine Chapter's fortress-monastery. For some Chapters the world also serves as their sole recruiting world; other Chapters draw their recruits from several planets. A "Chapter Planet" is an Astartes world which is both governed by the Chapter as a feudal possession of the Imperium of Man and which serves as the base for their fortress-monastery. Astartes homeworlds may be Imperial planets, while some are not planets at all, but take the form of orbiting spacecraft, space stations, deserted moons or asteroids.

The Master of the Chapter is often also the traditional feudal ruler of the Chapter planet, in which case the Chapter Master also holds the rank of planetary governor and Imperial Commander. Many Astartes homeworlds are also classed as Death Worlds, Feral Worlds and Feudal Worlds, whose societies provide the best warriors.

Not all Space Marine Chapters have a single homeworld; some Chapters such as the Imperial Fists, Black Templars and Blood Ravens take their aspirants from several different worlds. Fleet-based Chapters like the Black Templars do not possess homeworlds, and instead recruit from any convenient and promising worlds they pass near in the course of their duties.

Several Space Marine Chapters guilty of crimes against the Emperor (but those still deemed redeemable by the Inquisition and the High Lords of Terra), such as the Mantis Warriors and Executioners, have been forced to forfeit their homeworlds -- which requires them to become completely fleet-based Chapters.

For examples see: Baal, Fenris, Macragge

Death Worlds

Planets which are too dangerous for a variety of environmental and biosphere reasons to support widespread Human settlement are called Death Worlds. The types of Death Worlds are varied, ranging from planets that are covered by world-wide jungles that harbour vicious carnivorous plants and animals to barren rockscapes strewn with volcanoes and wracked by ion storms. These worlds are near-impossible to colonise by Mankind due to their environmental conditions or the nature of their biospheres. Nonetheless, many of these worlds have large Human settlements, which are notable for the strength and self-reliance of their people.

Many of the people of these worlds are inducted into the Astra Militarum, or recruited by the Space Marines, a fact which is often the sole reason for the continued habitation of those worlds. Some harbour rich mineral, vegetable, animal or gaseous resources that are of such value to the Imperium that a small Human settlement will be maintained despite all the dangers.

It has been theorized by the Magos Biologis of the Adeptus Mechanicus that many Death Worlds are the result of biological seeding by ancient advance hive fleets of the Tyranids that entered the Milky Way Galaxy long ago. Many of the monstrous creatures inhabiting these worlds, such as the Kraken of Fenris and the Catachan Devil of the Jungle World of Catachan, have many features in common with Tyranid organisms, and may in fact be descended from them. Left behind by the hive fleets that seeded these worlds and then moved on, these Tyranid species lost access to the Tyranid Hive Mind and so degenerated into unintelligent yet vicious animal species.

For examples see: Catachan, Cretacia and Karrik

Swamp Worlds

A Swamp World is not an official Imperial planetological classification, but a term in common usage among Imperial citizens for those planets whose environments are characterized by high heat and humidity and in which the majority of the surface is covered by swamps, marshes and bogs. Vast extents of nigh-impenetrable swamp territories is the main, distinctive feature of these worlds. Swamp Worlds are often inhabited by many dangerous creatures.

Due to the convoluted nature of the Imperial planetological classification system, Swamp Worlds can be given this classification or can be listed as a sub-category of Death Worlds if their native flora and fauna are particularly aggressive and predatory.

For examples see: Dulcis, Galmor

Chem Worlds

A Chem World is an Imperial planetological classification used as a sub-classification for certain Industrial Worlds whose atmospheres have been poisoned by the industrial waste of billions of people that has been pumped out of their manufactoria for standard millennia.

Described as being the Imperium's oubliettes and the filthiest of its worlds, Chem Worlds' populations must wear helmets or respirators at all times when outside in order to safely breathe their atmospheres. Needless to say, the life spans of the inhabitants of Chem Worlds are some of the shortest in the Human-settled galaxy.

For examples see: Adrion

Mining Worlds

Mining Worlds are rich in one or more of the raw strategic materials required by the Imperium's manufactoria and Forge Worlds. The people of Mining Worlds are likely to be slaves or penal workers of the Adeptus Arbites who live out their lives mining and transporting massive quantities of metallic ore, rock, minerals, frozen gases or some other useful, strategic or precious substance.

Mining Worlds tend to be rather inhospitable places, and many do not even possess a breathable atmosphere, though a few may support a greater variety of life, developed cities and even hive cities.

For examples see: Betalis III, Landunder, and ND0/K4

Industrial Worlds

Industrial Worlds are planets of the Imperium of Man that are not part of the Adeptus Mechanicus' semi-autonomous domain but whose surfaces are devoted wholly to manufacturing or heavy mining and refining activities. These worlds have surprisingly sparse populations in relation to Hive Worlds or Forge Worlds, as most of the labour is done using machines and other forms of advanced automation.

Those Industrial Worlds whose primary function is mining and refining are usually blessed with an unusually abundant reserve of highly strategic minerals in order to justify the expense of the investments in technology, labour and other resources.

For examples see: Vostroya, Endymion Prime

Waste Worlds

Waste Worlds are planets of the Imperium of Man whose surfaces are devoted wholly to the dumping and storage of unusable materials, chemical and biological wastes, and other useless and toxic manufacturing by-products.

There is little information on these planets in Imperial records and it is unknown if these planets have any inhabitants or if any recycling efforts are undertaken by the Imperium or the Adeptus Mechanicus.

For examples see: Hattusa

Forbidden Worlds

The existence of Forbidden Worlds, also called Quarantined Worlds, is rarely made obvious to Imperial citizens but there are many of them throughout Imperial space. Travel to these worlds is forbidden except for the most well-informed and heavily armed expeditions, and even then only with a very good reason. Death Worlds, alien empires or planets where the entities of the Warp have broken through into realspace are all examples of Quarantined Worlds, as are planets wracked with plague.

Some worlds are quarantined because no one can fathom the origins of what has been found there, be it mysterious artefacts or ancient alien cities -- it is thought better to live in ignorance of what lies on such worlds than risk it becoming a threat. Other worlds are quarantined because every expeditionary mission there has failed to return.

Planets are often quarantined by the pronouncements of the Inquisition, especially if they have uncovered some Warp taint or xenos infestation that cannot be cleansed. Many Forbidden Worlds possess great resources that would be extremely valuable to the Imperium if they were properly explored and exploited, but there are enough tales of ancient horrors awoken on sinister alien worlds that few adepts would try to defy a planetary quarantine.

For examples see: Sacris, Haxan Prime, Gonomondium

Frontier Worlds

Frontier Worlds are planets that have only recently been discovered by the Imperium of Man through the explorations of Adeptus Mechanicus Explorator fleets or Rogue Traders and are home to a relatively small number of Imperial colonists. The Administratum may not have even had sufficient time to fully explore the world and set up an Imperial planetary government.

Frontier Worlds can serve as a refuge for those who want to escape from the repressive Imperial regime (for a time at least), though they can also be a destination for those who want to escape its justice, and have a reputation for lawlessness and crime as a result.

For examples see: Orask, Vaxanide, Gladius Prime

Desert Worlds

A Desert World is not an official Imperial planetological classification, but is a term in common usage among Imperial citizens for those planets whose environments are arid and barren across their entire surfaces. Since the term "Desert World" is not an official Imperial classification of the Administratum but simply a label used to describe the planet's predominant environmental feature, most Desert Worlds that have been settled by Mankind are officially classified as Civilised Worlds, Feral Worlds or even Death Worlds if the environmental conditions are hostile enough to Human life.

Desert Worlds often produce hardy peoples superbly adapted to combat in arid conditions and so become prime recruiting grounds for the Astra Militarum when it needs desert-adapted regiments. Most Desert Worlds occur naturally, but a few once possessed very different climates that were radically altered by events, such as the planet Tallarn, which had its planetary forests destroyed by the virus-bombing campaign of the Iron Warriors Traitor Legion during the Horus Heresy.

For examples see: Tallarn, Tarentus, Thoth

Ice Worlds

An Ice World is not an official Imperial planetological classification, but is a term in common usage among Imperial citizens for those planets whose environments are frigid and glacier-covered across their entire surfaces. Since the term "Ice World" is not an official Imperial classification of the Administratum but simply a label used to describe the planet's predominant environmental feature, most Ice Worlds that have been settled by Mankind are officially classified as Civilised Worlds, Feral Worlds or even Death Worlds if the environmental conditions are hostile enough to Human life.

Ice Worlds often produce hardy peoples superbly adapted to combat in below-freezing conditions and so become prime recruiting grounds for the Astra Militarum when it needs cold-adapted regiments.

For examples see: Valhalla, Lorn V

Ocean Worlds

An Ocean World is not an official Imperial planetological classification, but is a term in common usage among Imperial citizens for those planets whose environments are a single, globe-straddling ocean across their entire surfaces, with perhaps only a few small archipelagos of islands serving as the only land masses.

Since the term "Ocean World" is not an official Imperial classification of the Administratum but simply a label used to describe the planet's predominant environmental feature, most Ocean Worlds that have been settled by Mankind are officially classified as Civilised Worlds, Feral Worlds or even Death Worlds if the environmental conditions or extant marine biosphere are hostile enough to Human life.

Ocean Worlds often produce hardy peoples superbly adapted to combat in marine environments and so become prime recruiting grounds for the Astra Militarum when it needs regiments for amphibious or underwater operations.

For examples see: Talassar, Ithaka, Tyran

Maiden Worlds

Maiden Worlds, or Lilaethan in the Aeldari Lexicon, are the lush paradise worlds originally created through advanced terraforming techniques from lifeless Dead Worlds by the Aeldari before the Fall of their race's ancient interstellar empire in the 30th Millennium.

The creation of these worlds involved seeding formerly barren planets with life, gradually leading to their transformation into lush, life-supporting worlds. The seeding of worlds was part of a program of colonisation which would take many thousands of Terran years to reach fruition, and the result would only be seen by much later generations of Aeldari, though in fact many of these worlds ended up being settled by other sentient races like Humans and Orks, much to the Aeldari's chagrin and anger. Many of the Maiden Worlds are today the homeworlds of the rustic Aeldari Exodites.

For examples see: Hannibal, Twenty-Eight Four, Torvendis

Crone Worlds

The Crone Worlds are the original homeworlds first colonised by the Aeldari as they rose to power millions of Terran years ago. The Crone Worlds formed the heart of the lost Aeldari Empire before they were consumed by the creation of the vast Warp rift called the Eye of Terror following the birth of the Chaos God Slaanesh. The worlds are now known as Crone Worlds to the Aeldari after Morai-Heg, the Aeldari goddess of fate.

The entire region where the Crone Worlds were located in the northwestern region of the galaxy was overtaken by the growth of the Eye of Terror, and the Aeldari Empire's homeworlds were consumed by Chaos and turned into nightmarish realities that now lie fully within the bounds of the Immaterium. The Crone Worlds seem to be synonymous with the planets now designated as Daemon Worlds by the Imperium of Man. They are now the domains of the Ruinous Powers and their servants along with many ancient Aeldari who have been trapped within the Warp since the Fall of the Aeldari and now desperately yearn for the sweet release of death and the consumption of their soul by Slaanesh.

These worlds remain vitally important to the survival of the Craftworld Aeldari in particular as they are the only source of new spirit stones. However, journeys to the Crone Worlds constitute entering the most dangerous area of the galaxy, and many of the Craftworld Aeldari who go to the Crone Worlds seeking new spirit stones or other valuable artefacts of their people never return. Besides the spirit stones, many other valuable artefacts of the ancient Aeldari civilisation survived the Fall of the Aeldari and still exist somewhere on the Crone Worlds for the taking, if any dare to claim them.

Xenos Worlds

A Xenos World is the designation given to a planet by the Adeptus Administratum that lies outside of the bounds and control of the Imperium of Man and that is the homeworld or colony world of an intelligent alien species. Most intelligent alien races inhabit only a single world that is their original homeworld, or a small group of worlds that they have recently settled in star systems close to their homeworld.

The majority of intelligent alien species are comparatively technologically primitive, unaggressive or lack any true power in the interstellar arena, which means they are of no interest to the Imperium unless they are occupying unusually resource-rich worlds or otherwise possess something the Imperium needs or represent a threat to the lives and property of Mankind.

Only a few of the intelligent species in the galaxy are numerous enough, aggressive enough or powerful enough to serve as rivals of the Imperium who must be dealt with severely. Of these, by far the most common are the Orks, the Craftworld Aeldari, the Drukhari, the Necrons, the T'au and the Tyranids.

Daemon Worlds

A Daemon World as designated by the Inquisition is a planet twisted and corrupted by the power of Chaos and the Warp after being trapped in a prolonged Warp rift like the Eye of Terror. Entwining the impossibilities of the Warp and the reality of the material universe, Daemon Worlds are not bound by the natural laws of physics, but by the whim of daemonic rulers and the emotions of mortals' collective unconsciousness. Daemon Worlds are usually ruled by a Daemon Prince, who can shape the world to their liking.

Each of these worlds is a bizarre sub-reality ruled by terrible Daemon Princes. The four major Chaos Gods continuously compete to possess the Daemon Worlds. Armies of Daemons and their mortal allies fight huge and bloody battles to determine which of the Ruinous Powers will dominate them, adding the world to their realms within the Warp. These battles often last for hundreds of standard years, so that the entire world becomes little more than a gigantic arena where the opposing forces are pitched against each other.

The Ruinous Powers do not, of course, appear in person to lead their armies -- they are, as always, spectators to events, not participants. Their generals are Greater Daemons and favoured Daemon Princes who, because they were once alive as mortals, understand the nature of both the material universe and the Immaterium.

Once a Daemon Prince has conquered a Daemon World or brought a world from the physical universe into the Warp, his grateful divine patron gives it to them as a gift to rule over as they wish. When a Daemon Prince takes control of his hard-won world he uses his mighty sorcerous powers to reshape it into a form which pleases him. Because of this, every Daemon World is different and all are equally horrific in their own way.

For examples see: Plague Planet, Planet of the Sorcerers

Fallen Knight Worlds

The Fallen Knight Worlds are the homeworlds of the Chaos Knights. Just as some Knight houses have become corrupted by Chaos, so too were their worlds transformed into horrific mockeries of their former glory. Where once the denizens of these planets had looked to their Nobles for leadership and protection, they were swiftly reduced to a terror-filled existence.

The populations of entire cities were hunted for sport by their Knightly overlords. Fallen Nobles supplied tithes of living Humans to their heretical lieges to be used in sadistic rituals or the forging of daemonic pacts. Where once the would-be Knight pilot prepared for their duty over standard years of training, and proved their worth in solemn duels, they now engaged in competitive slaughters of their own subjects.

Depraved cultures took root in every echelon of society on these Chaos Knight worlds. Teeming Chaos Cults worshipped the Dark Gods openly, Fallen Nobles competing to raise the greatest temples to the Ruinous Powers.

The landscapes became pocked with charnel pits that overflowed with the corpses of defeated enemies. These planets that had been bastions of order throughout the Age of Strife metamorphosed into deep wells of anarchy, from which the taint of Chaos seeped further into reality. Korvosi,

For examples see: Korvosi, Dharrovar


A Hell-Forge is a fallen Forge World dedicated wholly to the Ruinous Powers and controlled by the Dark Mechanicum. Most of these Hell-Forges lie in the Eye of Terror located in the Segmentum Obscurus or the Hadex Anomaly in the Jericho Reach.

These infernal forges of the fallen Heretek scions of the Cult Mechanicus reek with the terrible smells of burning blood and scorched flesh, fed by souls as well as promethium and steel, constantly churning out arms, armament and Daemon Engines for their Dark Mechanicum lords and their Traitor Legion allies.

The ubiquitous holy symbol of the blessed cogwheel, the Cog Mechanicum, is gone; replaced by leering metal skulls set in a circlet of spiked teeth. But the worst thing is that there is no proper, logical structure to the world. Forge cities rise in random fashion, lurching towards the skies and deep into the planetary crust at the whims of their Dark Magi lords. To the Adeptus Mechanicus, these Hell-Forges are a dark mirror of their own holy Forge Worlds, one they dare not contemplate too closely.

For examples see: Xana II, Cyclothrathe


  • Dark Heresy Core Rulebook (RPG), pp. 249-250
  • Imperial Armour Volume One - Imperial Guard & Imperial Navy, pp. 10-12
  • Imperial Armour Volume Five - The Siege of Vraks - Part One
  • Only War: Core Rulebook (RPG), pp. 322-323
  • Warhammer 40,000: Rogue Trader (1st Edition), pg. 134
  • Warhammer 40,000 Rulebook (6th Edition), pg. 153
  • White Dwarf 305 (UK), pp. 64-65
  • 500 Facts for 500 Stores! - Fact 45, Fact 46

Worlds of the Galaxy
General/Environmental Classifications Chem WorldDead WorldDeath WorldDesert WorldDerelict WorldIce WorldForest WorldJungle WorldMountain WorldOcean WorldRad WorldSwamp World
Imperial Classifications Abattoir WorldAdeptus Astartes HomeworldAgri-worldAnchor WorldArboreal WorldArchive WorldArmoury WorldAstropathic Relay StationBattery WorldCardinal WorldCemetery WorldCivilised WorldDelverworldFeral WorldFeudal WorldForbidden WorldForge WorldFortress WorldFrontier WorldHive WorldHub-FortressIndustrial WorldKnight WorldLabyrinth WorldLumber WorldMenagerie WorldMerchant WorldMining WorldPenal WorldPenitent WorldPleasure WorldQurantined WorldQuarry WorldRefugee WorldRepository WorldResearch StationSentinel WorldShrine WorldWar WorldWaste World
Chaos Classifications Daemon WorldHell-ForgeFallen Knight World
Xenos Classifications CraftworldCrone WorldExodite WorldHold WorldKin WorldMaiden WorldOrk WorldT'au SeptSept WorldTomb WorldXenos World