"By decree of the Lords of Askellon and the most Holy Inquisition, this world is now deemed to be under Imperial Quarantine. Any who violate this edict are considered Perditious and their lives deemed forfeit."
— Final words of an Askellian Writ of Quarantine
War World-Forbidden World

A Forbidden World

A Forbidden World, also called a Quarantined World, is a planet that has been declared off-limits to contact with Imperial citizens by the government of the Imperium of Man, usually by the express order of the Inquisition. The existence of Forbidden 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 creatures 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 Imperial 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, particularly one backed by an Inquisitorial warrant.

Quarantine worlds are marked as forbidden for visitation, settlement, or contact of any kind. Some might be seemingly benign verdant spheres, others might be foreboding rocks, but the Imperium has determined there is some terrible threat that outweighs any possible usefulness they might contain. Such threats range from biological agents to xenos species infiltration, and even to possible Warp-taint and other unholy threats. Whatever the catastrophe, potential or historical, it is viewed as a far greater risk than any reward it could bring.

Once the edict is given, the Imperial Navy provides the military and defence systems the situation requires, from message buoys at the outskirts of the system to patrolling ships and orbiting weapons platforms. No unauthorised craft is allowed anywhere near the space and any found are generally destroyed without question. In case of extreme risk to the sector, the human population is often annihilated to prevent any potential escape attempts. Regardless of whether anyone survives this culling, no one is allowed to set foot on those planets without proper authorisation. To be discovered breaking a writ of quarantine is a death sentence.

Life on a Quarantine World

Details of life on quarantine worlds are scarce, as most who could provide them are trapped on the surface or captured and likely put to immediate death if found to have escaped. Tales whisper of worlds covered with psychic storms that can burn sanity like firewood, or where ethereal remnants of dead races still stalk the ruins of once-grand temples, or simply where events occurred so terrible that the Imperium insists they remain secret forever.

Populations might vary from teeming masses unknowingly tainted with a Warp-based plague to the wretched survivors of an alien invasion deemed too spiritually contaminated to be allowed outside contact. Though Inquisitors often seek to interrogate such individuals for information about the world they came from and how they were able to escape from it, most captains readily dispose of them through an air gate should any official investigations draw near their ship.

On some quarantine worlds, the remaining inhabitants are perhaps unaware of their status, knowing only that travel from their planet has been dormant for long generations and such is the way the Emperor has decreed. On others, where the populace knows of their fate, many lose hope quickly and sacrifice themselves in an attempt to thwart any spread of the threat. A few, however, may be motivated to find a way to beat the odds and counteract the threat, whether it is killing the creature or pathogen or containing and eradicating Warp contamination. There are no records of any world ever being released from quarantine, though many planets have petitioned for generations, claiming that they have freed themselves of any taint.

Escape from a quarantine world, however, is very different. Leaving under one’s own power is usually met with death at the hands of gunners or interceptor pilots. Any craft detected leaving the planet’s surface is hailed once and then eliminated. Stationed forces, however, must conduct reconnaissance themselves, whether by scans from orbit or aerospace drones and aircraft doing more in-depth sensor sweeps and visual checks from within the atmosphere. It is in these instances that the local populations may attempt to commandeer or stow away aboard these craft, seeking a one-way ticket to the larger orbiting ship where they can hopefully disappear within the ship’s crew.

People from worlds marked for quarantine face immeasurable odds in getting off planet and staying free. Whether the individual lived there at the time of the event, was born afterward, or has been to the surface “liberating” inhabitants or scavenging for ancient relics, anyone who has been past the restriction points of the edict lives on borrowed time. Depending on the nature of the quarantine and the amount of ordnance preventing departure, those who flee risk capture and execution, and therefore must remain on the run. It is no surprise that they seldom ally themselves with any singular group for too long.

Anyone can come from a quarantine world, for it is the nature of the world or the accident that determines the need for enforced segregation, not the people. Adeptus Mechanicus research stations, agri-worlds, hive worlds…all of these have been the victims of such accidents, condemning their inhabitants to lives of gradual decline and eventual extinction. Those who survive and escape are some of the most versatile and resourceful people in the galaxy. They are also some of the least trusting and secretive, relying on themselves and often willing to strand comrades in order to stay one step ahead of the authorities. In the rarest of circumstances, the Left Hand of the Emperor finds these individuals and offers them a chance to stop running in exchange for their services. It is a very brave or very foolish person who refuses such an offer.

Known Forbidden Worlds

Planet Name Segmentum Sector Sub-Sector System Population
47 Kapella Segmentum Obscurus Calixis Sector Drusus Marches Unknown Unknown
Abandoned Hope Segmentum Obscurus Calixis Sector Josian Reach Unknown Unknown
Barbarus Segmentum Tempestus Unknown Unknown System Classified (Ageisine/Black) 0
Carrion Deep Segmentum Tempestus Unknown Unknown Unknown None
Chemos Ultima Segmentum Unknown Unknown Chemos System (Classified - Ageisine/Black) 0
Colchis Segmentum Pacificus Unknown Unknown Colchis System (Classified - Ageisine/Black) 0
Cthonia Segmentum Solar Unknown Unknown Cthonic System (Classified - Ageisine/Black) 0
Farcast Segmentum Obscurus Calixis Sector Malfian Sub-Sector Unknown Unknown
Gelmiro Primus Segmentum Obscurus Calixis Sector Markayn Marches (Spinward) Unknown Unknown
Gelmiro Secundus Segmentum Obscurus Calixis Sector Markayn Marches (Spinward) Unknown Unknown
Gelmiro Tertius Segmentum Obscurus Calixis Sector Markayn Marches (Spinward) Unknown Unknown
Gonomondium Unknown Unknown Unknown Unknown Unknown
Haxan Prime Unknown Unknown Unknown Unknown Unknown
Kulth Segmentum Obscurus Calixis Sector Periphery Sub-Sector Unknown Unknown
Kuluth Segmentum Obscurus Calixis Sector Malfian Sub-Sector Unknown Unknown
Malice Segmentum Obscurus Calixis Sector Hazeroth Abyss Unknown Unknown
Nuceria Ultima Segmentum Unknown Unknown Nuceria System (Classified - Ageisine/Black) 0
Olympia Ultima Segmentum Unknown Unknown Olympia Majoris System (Classified - Ageisine/Black) 0
Prospero Ultima Segmentum Unknown Unknown Prospero System (Classified - Ageisine/Black) 0
Protasias Segmentum Obscurus Calixis Sector Drusus Marches Unknown Unknown
Sacris Segmentum Obscurus Calixis Sector Drusus Marches Unknown Unknown
Simia Orichalcae Unknown Unknown Unknown Unknown Unknown
Vapaus Segmentum Obscurus Askellon Sector Unknown Vapaus System Unknown


  • Codex: Space Marines (3rd Edition)
  • Dark Heresy: Core Rulebook (RPG), pg. 250
  • Dark Heresy: Enemies Beyond (2nd Edition) (RPG), pp. 30-31
  • Deathwatch: First Founding (RPG), pg. 92
  • Horus Heresy: Collected Visions, pp. 70, 226
  • Imperial Armour Volume Ten - The Badab War, Part Two, pp. 88-89
  • Index Astartes I, "Children of the Emperor - The Emperor's Children Space Marine Legion", "Bitter and Twisted - The Iron Warriors Space Marine Legion"
  • Index Astartes III, "The Lost and the Damned - The Death Guard Legion"
  • Index Astartes IV, "Dark Apostles - The Word Bearers Space Marine Legion", "Sons of Horus - The Black Legion Space Marine Legion", "Chosen of Khorne - The World Eaters Space Marine Legion,"
  • The Horus Heresy - Book One: Betrayal, Inside Cover Map, pp. 66-68, 104-105, 122-127
  • The Horus Heresy - Book Two: Massacre, pg. 138
  • The Horus Heresy - Book Three: Extermination, pp. 53, 107-110, 119, 129
  • Warhammer 40,000 Rulebook (6th Edition), pg. 153
  • White Dwarf 274 (US), "Iron Within, Iron Without"
  • White Dwarf 257 (AUS), "Index Astartes – Iron Warriors"
  • Horus Rising (Novel) by Dan Abnett
  • False Gods (Novel) by Graham McNeill
  • Galaxy in Flames (Novel) by Ben Counter
  • The Flight of the Eisenstein (Novel) by James Swallow
  • Fulgrim (Novel) by Graham McNeill, pp. 327, 355
  • A Thousand Sons (Novel) by Graham McNeill
  • Prospero Burns (Novel) by Dan Abnett
  • The First Heretic (Novel) by Aaron Demski-Bowden, pg. 320
  • Aurelian (Novella) by Aaron Demski-Bowden
  • Butcher's Nails (Audio Drama) by Aaron Dembski-Bowden
  • Betrayer (Novel) by Aaron Dembski-Bowden
  • Angel Exterminatus (Novel) by Graham McNeill, pp. 19, 37, 39, 54, 56-57, 118, 206, 238, 264-266
  • Caves of Ice (Novel) by Sandy Mitchell
  • Dark Heresy: Forbidden Worlds (Link Defunct)

General Dead WorldDeath WorldDesert WorldIce WorldJungle WorldOcean World
Imperium Adeptus Astartes HomeworldAgri-WorldArmoury WorldCardinal WorldCemetery WorldCivilised WorldFeral WorldFeudal WorldForbidden WorldForge WorldFortress WorldFrontier WorldHive WorldIndustrial WorldKnight WorldMining WorldPleasure WorldPenal WorldQuarry WorldResearch StationSentinel WorldShrine World
Chaos Daemon World
Xenos CraftworldCrone WorldExodite WorldMaiden WorldOrk WorldTau SeptTomb WorldXenos World
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