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*''White Dwarf'' (UK) 114, "Genestealers," by Paul Murphy, pp. 31-37
*''White Dwarf'' (UK) 114, "Genestealers," by Paul Murphy, pp. 31-37
*[http://redelf.narod.ru/w40k/ix/ix_genestealer.html ''White Dwarf ''266, "The Genestealer - Ultimate Predator" Article]
*[http://redelf.narod.ru/w40k/ix/ix_genestealer.html ''White Dwarf ''266, "The Genestealer - Ultimate Predator" Article]
*[http://members.fortunecity.com/pangolinsaloon/fl/genestealers.htm ''White Dwarf'' 114, "Genestealers" Article]
*[http://web.archive.org/20040301021207/members.fortunecity.com/pangolinsaloon/fl/genestealers.htm ''White Dwarf'' 114, "Genestealers" Article]

Revision as of 14:02, 10 November 2013

"I can think of few greater xenos threats to the Imperium than that of the Genestealer. An apex predator possessed of intelligence and cunning that rival our own, they exist for the sole purpose of reproducing in vast numbers and sowing utter chaos in their wake."

— Inquisitor Kalistradi from the The Nature of the Beast

A Genestealer prepares to pounce on its unsuspecting prey

The Genestealers (Corporaptor hominis) are one bioform of the multispecies Tyranid race that was genetically designed by the Hive Mind for the infiltration of other intelligent species' settled worlds. The Tyranids are an intelligent, nomadic alien race governed by a collective consciousness known as the Hive Mind and comprising many different genetically-engineered forms. Genestealers reproduce by introducing their genetic material into a host from another intelligent species; this is normally a human, but can theoretically be any sentient humanoid race, including the Eldar or the Orks. The Genestealers have no true genders, and require a creature of any species, any gender to reproduce. The Genestealer will find a suitable host and hypnotise them into passivity using its unusual, alien eyes. The Genestealer then thrusts its long, whip-like tongue (which also serves as an ovipositor) into the body of the host, where it deposits its DNA in the form of a type of virus that infects the somatic and germ line cells of the host. Several hours later, the infected victim wakes up from the incident, with no wounds or any recollection of what happened. The new host of the Genestealer DNA will go on about its normal life, and eventually reproduce with another member of its species, thus siring (if male) or giving birth (if female) to a Genestealer Hybrid. The Genestealer reproductive cycle is truly cyclical, as an F4 hybrid will always spawn a purestrain Genestealer with a genome identical to that of the original Genestealer that infected the first host.


A Tyranid Genestealer on the hunt

Few Tyranid creatures have earned such a terrible reputation or caused as much damage to the Imperium of Man as the Genestealer. Detected long before the first tendrils of the Hive Fleets reached the galaxy, they were thought to be little more than another unusual and deadly alien xeno-form. It was only after the horrors of Hive Fleet Behemoth and Hive Fleet Leviathan assaulted the galaxy that the Imperium came to realise their true purpose as advanced scouts for the Hive Mind and xenos infiltrators of the most insidious kind. Hiding away on void ships and in the depths of Space Hulks, the Genestealer menace has travelled across the length and breadth of the Imperium, seeding themselves onto human worlds and subverting their populations. This perhaps is the greatest horror the Genestealers bring, as they can infect almost any lifeform with a "kiss," implanting some of their own genetic material into the host and taking complete control of its reproductive system. When the host gives birth to offspring, these carry with them the Genestealer's genes and over the course of several generations a new Genestealer is born, albeit with some genetic traits taken from its host: such as the human-like hands many Genestealer Hybrids encountered in the Imperium possess.

Cunning and independent, Genestealers are also one of the few Tyranid bioforms that can exist away from the nurturing and controlling influence of the Hive Mind, using their own innate intelligence and brood telepathy to form tight-knit groups. These groups can survive for decades or even centuries on worlds, hiding their presence and infecting more and more of the population until the time to strike arrives, usually coinciding with the arrival of a Hive Fleet and the wholesale invasion and consumption of the world by the Great Devourer, Genestealers and humans alike.

Genestealer Physiology

A typical Purestrain Genestealer specimen

Genestealers, like virtually all Tyranid organisms, are characterised by their six limbs and resilient carapace. They are bipedal and able to move with lightning speed on their reverse-jointed, clawed lower limbs. The upper sets of limbs are distinctly different, the foremost pair ending in razor-sharp claws capable of slicing through even Tactical Dreadnought Armour (ref. MGP.Macragge. 1st Company.qv). Their secondary limbs are typically shaped like gnarled hands, allowing the Genestealer to manipulate objects, climb and even operate simple devices such as touch-panels. The number of digits differs depending on the parent organism. Despite their dexterity, these secondary limbs are still more than capable of ripping a limb from its socket. The thickly-muscled tail appears to be vestigial, although could aid the balance and agility shown by all variations of the species.

The colour of the Genestealer varies depending on its parent Hive Fleet. Specimens have been reported ranging from bone-white to jet black. Perhaps the most successful strain of Genestealer is typified by a blue-indigo coloration. This strain has been encountered on numerous Space Hulks and is possibly specifically nomadic; bio-engineered purely to infect new hosts.

A Genestealer's characteristically bulbous head

A Genestealer's head is characteristically bulbous and houses a disproportionately large brain for such a single-minded creature. Its jaws are lined with viciously sharp teeth, all designed for ripping and tearing; like other Tyranids they only have incisors, not molars.

Their carapace, along with the density of their internal skeleton, typically thickens with body mass; a Genestealer whose host was Orkoid will typically be tougher than one born of Eldar gene-stock. Underneath this is the fibrous muscular sheath that can be compared to standard Imperial Flak Armour in terms of durability. These layers provide a considerable degree of protection; combined with their naturally tough physique it is possible for a Genestealer to charge headlong through a volley of Lasgun fire and survive. As with other Tyranid organisms, they typically have an open circulatory system with haemolymph flooding the intercellular spaces. This system is host to unnumbered phage cells, believed by the Magos Biologis of New Hallefuss research facility to be digestive systems. These allow them to feed on the nutrient-rich end product of a Tyranid invasion. Closer investigation shows the phage cells to have a dual purpose, acting in a manner similar to fibrinogens in the human bloodstream and clotting the liquids that seep from any wounds that the Genestealer has suffered (ref.MBfl277.anticoagulant.hellfire.qv).

Another physiological anomaly that Genestealers display is the redundant respiratory and circulatory systems irfherited from their host species. Furthermore, they exhibit vestigial digestive systems. Some specimens even have complete stomachs, although these are superfluous given the efficiency of the phage cell. These expendable systems allow the Genestealer to sustain considerable non-lethal damage and still function. It is widely known by Imperial forces that those coming into conflict with Genestealers should direct their fire towards the thorax and abdomen of the beasts, as even with several extremities missing they are still highly dangerous opponents.

Thanks to the capture of live Tyranid specimens by the Draco Legion Chapter of the Adeptus Astartes, it is known that Genestealers are able to feel pain and react adversely to its application, either becoming incredibly aggressive or cowed into temporary submission. Genestealers have a tremendous tolerance for cold, allowing them to survive in the void of deep space, hidden within the bowels of the Space Hulks they typically infest. They are even able to survive in a vacuum for a short space of time. To truly exploit the space detritus it inhabits, a Genestealer has great longevity and also the ability to endure long periods without nourishment. A Genestealer can also enter a torpid state at will, lowering its metabolic rate dramatically. Therefore, they are able to survive long periods of inactivity and hardship until new prey enters their lair.

Reproduction Cycle

A Genestealer Ovipositor as dissected by an Adeptus Mechanicus Magos Biologis

Genestealers reproduce by introducing their genetic material into a host from another intelligent species; this is normally a human, but can theoretically be any sentient humanoid race, including the Eldar or the Orks. The Genestealers have no true genders, and require a creature of any species, any gender to reproduce. The Genestealer will find a suitable host and hypnotise them into passivity using its unusual, alien eyes. The Genestealer then thrusts its long, whip-like tongue (which also serves as an ovipositor) into the body of the host, where it deposits its DNA in the form of a type of virus that infects the somatic and germ line cells of the host. Several hours later, the infected victim wakes up from the incident, with no wounds or any recollection of what happened. The new host of the Genestealer DNA will go on about its normal life, and eventually reproduce with another member of its species, thus siring (if male) or giving birth (if female) to a Genestealer Hybrid. The Genestealer reproductive cycle is truly cyclical, as an F4 hybrid will always spawn a purestrain Genestealer with a genome identical to that of the original Genestealer that infected the first host.

Newly born Genestealer Hybrids, although fundamentally Genestealers, will have characteristics inherited from the host parent. Thus a Genestealer Hybrid of human stock may have a vaguely humanoid head, or only two arms instead of the usual four, and perhaps its tail will be shortened or missing. A Genestealer of four or more generations of consistent human parentage would pass for a baseline human on cursory inspection, although a closer look would reveal bluish skin, sharp, pointed teeth and a rather disturbing stare. The Ymgarl Genestealers on their homeworld exploited a large, semisentient leech-like creature called a Csith as their usual mate; and matings with a Csith always produce natural Ymgarl Genestealers rather than Hybrids, no matter what the parentage of previous generations.

Combat Capabilities

Genestealers do not rely purely on their deadly speed and vicious, ripping claws to defeat their enemies. They are possessed of considerable intelligence, comparable to that of Lupus fenrisii (Fenrisian Wolves), and are able to coordinate stealthy attacks and set traps when hunting their prey. It is postulated that they convey information telepathically since no other form of communication has been observed thus far. This "brood intelligence" is thought to be akin to the gestalt consciousness of the Hive Mind, only on a far smaller scale. The Genestealer brood can therefore act as an autonomous unit, able to function light years away from the synapse control of the larger Tyranid creatures.

Much of the Imperium's information on the combat abilities of the Genestealer has been supplied by the 1st Company of the Blood Angels Space Marine Chapter. They have performed numerous expeditions into the depths of Space Hulks such as Spawn of Execration, Charybdis, Immeasurable Hatred, Sin of Damnation and Harbinger of Despair. Decorated with the Blood Star after his success in leading missions into the heart of two of the aforementioned Hulks, Captain Lorenzo of the Blood Angels has filed comprehensive reports on the tactics used by these aliens and the lethal threat they pose.

The Genestealer will not hibernate until it is absolutely familiar with its surroundings, including in-depth knowledge of the ventilation systems, sewers and other crawlways that surround the Space Hulk's corridors. In this way they can surround and ambush their prey, whose knowledge of the voidship's labyrinthine passageways is often woefully inadequate. This allows them to close incredibly rapidly, denying their foe the opportunity to cut them down with ranged weaponry. Once the Genestealer is in close combat, it utilises its clawed forelimbs to rip apart its opponents. The three claws on each forelimb are incredibly sharp and diamond-hard, able to slice through bulkheads and cut through the thickest armour. Combined with the awesome strength afforded by the efficiency of the Genestealer's musculature, it is quite feasible for a Genestealer to rip its way through the side of a Chimera to get to the troops inside. The survivors of a Genestealer attack are inevitably heavily armed, forewarned and well-trained, or have become a host carrying purestrain seed.

Although the characteristic claws of the Genestealer are its primary weapons, certain variations in the xenomorph's form have been reported across the galaxy. Long, stabbing talons occasionally replace the Genestealer's secondary limbs, and several specimens have been found on Ork-infested Space Hulks with thicker carapaces. In 234.921.M41, a Genestealer was captured that carried virulent inorganic poisons and haemotoxins in sac-like pouches on is arms. Another known genus can shoot thick, barbed strands of sinew into their victims to keep them from moving freely as the Genestealer closes in for the kill. These "flesh hooks" are dispatched from the ribcage by a sharp intercostal muscle spasm, and can also aid the xenomorph in climbing walls and other vertical surfaces. Presumably these traits are either inherited in part from the host species, or bioengineered by the Hive Mind in its eternal quest for ever more deadly soldier-organisms.

Genestealer Sub-Species

Purestrain Genestealer

Purestrain Genestealers have the same basic arthopodic body structure as all other Tyranid species. They appear as roughly man-sized, six-limbed creatures with both the chitinous exoskeleton and endoskeleton common to Tyranids. Their two lower limbs are legs; another pair of limbs are extremely sharp claws which are used for tearing apart foes in close melee combat - these claws are so sharp that they can even hack through extremely well-armored enemies, such as Space Marine Terminators, with ease. The other set of limbs are arms as well, but their nature varies depending on the type of host species used to create the Genestealers or the needs of the Hive Mind. Genestealers are known for their incredible agility and great skill in close combat. Genestealers were first encountered by the Imperium of Man on the moons of Ymgarl. After this encounter, Genestealers were further encountered on large derelict starships known as "space hulks"- these ship-borne encounters being the subject of the aforementioned Space Hulk game. With the invasion of the Imperium of Hive Fleet Behemoth in the late 41st Millennium, it was discovered that the Genestealers were in fact a part of the Tyranid race. Genestealers perform two roles for the Tyranid armies: first, they are often found in the main Tyranid hive armies acting as assault troops; second, they can be found as an advance force of a Tyranid Hive Fleet, aiding future planetary invasions and biomass absorption through the use of their unusual reproduction method.

Ymgarl Genestealer

An Ymgarl Genestealer hybrid

Imperial researchers of the Adeptus Mechanicus have concluded that the Ymgarl Genestealer was a form of the species that became separated several hundred Terran years ago from the main fleet of the Tyranids' Hive Fleet Behemoth, and, having completely lost its psychic link to the Tyranid Hive Mind, had reverted to a feral state. Ymgarl Genestealers appear quite different from normal Genestealers, and this is also believed by the Imperials to be due to the separation from the Hive Mind, and generations of eating almost exclusively a native lifeform of the Ymgarl moons.

Genestealers are known to change over the generations. The different variations between broods can be quite marked, but Ymgarl Genestealers are truly unique because they possess the ability to alter their own flesh to react to incoming attacks or to change its colour like a chameleon so that it can blend into its surroundings and remain unseen until it escapes or attacks. Their claw-tipped fingers can suddenly elongate and fuse together to form curved blades and barbed hooks or split apart into tentacles of sinewy alien flesh to slash or entangle those victims who try to escape. Under assault their chitinous carapaces can thicken and help their leathery hides absorb the energy of incoming melee or ranged assaults. Some Imperial observers who have had contact with this creature have even reported this strain of Genestealer's ability to change the colour of their skins, so as to better go undetected in the darkness of night or other extreme light conditions.

But this extreme adaptability comes at a high price for this bioform. Ymgarl Genestealers must feed on large amounts of biomatter, and feed often. Ymgarl Genestealers' most distinctive feature is the mass of writhing tentacles that replaced the fanged mouth found on the standard strain of Genestealer which they use to pierce their victim's flesh to better feed upon the blood within -- this strain's only source of real nutrients. Those Ymgarl Genestealers that cannot obtain adequate nourishment to feed their raging metabolisms in this way will be forced to enter a state of dormant hiberation or starve to death. Within this state they will wait until something living -- and filled with fresh blood -- comes to disturb their dreamless sleep.

The origins of the Ymgarl Genestealers remain a complete mystery to Imperial savants, for they do not seem to have been a strain of bioform created by any of the Hive Fleets already known to have invaded Imperial space. It may be that they are the last survivors of a Tyranid reconnaissance of the galaxy before the arrival of Hive Fleet Behemoth. Even stranger, whilst the survival instincts of the other Genestealer strains leads them to flee the oncoming arrival of their parent Hive Fleets, Ymgarl Genestealers actively seek them out, as if they hope to once again hear the comforting presence of the Hive Mind that has long been absent from their thoughts. They spread across the galaxy searching for these inhabited planets that lie in the path of an approaching Hive Fleet. Once there they will lie dormant in hibernation until the Hive Mind reasserts contact with them and they can hunt alongside the rest of the Tyranid swarm. However, the Hive Mind has no desire to reabsorb their biomass or genetic legacies, lest their known instability spread throughout all of the bioforms in the Hive Fleet. Once the target world has had all of its biomass devoured, the Ymgarl Genestealer brood is abandoned by the Hive Mind, forced once more to enter hibernation. Unfortunately, many human starships often investigate the Dead Worlds left in the wake of a Tyranid attack. They come to learn more about the horrific xenos, in the forlorn hope of discovering some miraculous survivors or as scavengers come to pick over whatever wealth may remain. These fools and idealists often leave the world with a far more deadly cargo hidden within their holds, ready to spread the cycle of death and terror anew.

The Ymgarl Genestealers were at first not thought to be a part of the broader Tyranid race, but were instead thought to be xenos native to the moons of the world of Ymgarl. However, 200 standard years later, during the invasion of Hive Fleet Behemoth beginning in 745.M41, the Tyranids used Genestealers as shock troops and melee infantry in countless battles against the Imperium and the other intelligent races of the Milky Way Galaxy. The Magos Biologis of Mars spent many years trying to classify the Tyranid artefacts and bioforms left behind on Macragge after the invasion of Hive Fleet Behemoth was stopped by the sacrifices of the Ultramarines. Yet they could learn little about their origins from these remains. The only notable discovery had been that the Tyranids used the Genestealers as their shock troops. It had been believed that these xenos had spread across the galaxy onboard Imperial cargo barges and derelict Space Hulks. Many of the Imperium's most violent encounters with Genestealers before the arrival of the Tyranids had been onboard infested Space Hulks and names of such Hulks as the Sin of Damnation were forever synonymous with these deady aliens. The presence of Genestealers amongst the Tyranid bioforms proved that these previous assumptions concerning the Genestealers' independent origins had been false. Further genetic analysis confirmed that all Genestealers, even the tentacle-mouthed variant encountered amongst the moons of Ymgarl, were Tyranid bioforms.

In response to this news, the Space Marines of the Salamanders Chapter unleashed a xenocidal campaign to purge the moons of Ymgarl of the foul creatures and the Inquisitors of the Ordo Xenos intensified their search for any signs of new Genestealer infestations, but little else could be done to deal with the problem. The question that continues to perplex Imperial savants is whether the Ymgarl strain of Genestealers are the remainders of an unknown ancient Hive Fleet that entered the galaxy before Behemoth or whether there is more to the current Tyranid invasion than has yet to become apparent. Regardless of the outcome, the Ymgarl Genestealer strain was not completely destroyed by the Salamanders' efforts. They endure in the dark corners of the galaxy, always waiting for the chance to spread their infestation to new worlds and offer up yet another sacrifice for the Great Devourer. The truth about the Ymgarl strain has yet to be revealed.

Adrenal Genestealer

Adrenal Genestealer

Adrenal Genestealers are a newer strain that have emerged within the Tyranid armies: deathly agile and relentless, these dangerous new foes pop out from every dark corner, unleashing attack after attack. Attached to these deadly creatures are Adrenal Glands, a common Tyranid Biomorph which can be found on most of their front-line fighting creatures. Polyp-like organisms clamp themselves onto the host and secrete doses of a powerful adrenaline-like substance into it during combat, making the host creature relentless and nigh unstoppable in the heat of battle.

Vectori-Strain Genestealer

Vectori-Strain Genestealer

The Vectori strain represents a classification of Genestealers adopted by the Deathwatch of the Jericho Reach to refer to the unique Genestealer breed encountered aboard the Space Hulk Mortis Thule. More agile than the purestrains from which all Genestealers derive, this xenos breed is well adapted to moving swiftly and silently through confined spaces, while their lower body mass reduces the energy required of their metabolisms, allowing them to operate effectively for longer periods without sustenance. Vectori Genestealers are nimble and stealthy hunters, operating with a focus and efficiency natural to creatures for which economy of energy is an essential facet of survival. However, their lighter physiology makes them ill-suited to direct shock tactics, and their bodies are not as durable as those of other purestrains.


A Tyranid Broodlord

The Broodlord, or Corporaptor Primus, is the ultimate product of Genestealer evolution. The Broodlord is immensely strong, agile and durable, which makes it a superb melee warrior. In addition to their already potent melee combat abilities, the Broodlord also has a few Tyranid Biomorphs or biomechanical weapon-symbiotes to chose from beyond just its standard rending claws and scything talons.

The Broodlord acts as an assault commander for Tyranid armies, personally leading attacks while bearing the "synapse" ability frequently observed in higher forms of Tyranids which allows them to coordinate the Hive Mind's psychic commands over other, less-intelligent Tyranid species. However, unlike the traditional Genestealer Cult that rises up, takes its followers from among the local populace of an infested Imperial world and psychically dominantes them, and who then proceed to worship the Tyranids as gods, the army led by the Broodlord is an infiltrating vanguard that operates in a similar manner to the Tyranid Lictor.

Vectori-Strain Broodlord

The circumstances that lead to a Broodlord coming into being are still a relative unknown to the Ordo Xenos, but speculation and theories abound on the subject. In the case of those found aboard the Space Hulk Mortis Thule in the Jericho Reach, it has been theorised that exposure to the energies of the Warp and isolation from the Hive Mind has somehow culminated in the creation of an "alpha" Genestealer, a creature of terrible majesty and dreadful might that exists at the heart of the collective brood-mind shared by any given group of Genestealers. Whatever the truth of their origins, Vectori Broodlords are terrifying creatures. Connected psychically to an instinctive network of hunters, they lie in wait while their lesser brood herd unwitting prey into traps and ambushes orchestrated by a being of vicious cunning and inhuman intellect. When they choose to act directly, there are few combatants who can endure their onslaught.

Vectori-strain Genestealers have a constant telepathic link with each other which can function clearly and without restriction (such as from intervening objects or other forms of shielding) up to one kilometre. This allows them to communicate with one another and pass information to nearby Genestealers quickly and quietly. A Broodlord at the heart of this telepathic link can track its foes with the senses of many and employs its greater intellect to coordinate and command the lesser Genestealers.

Genestealer Cults

A Genestealers Cult on the rampage

A pack of Genestealers attack

All of the members of this unusual "family", including human hosts, Hybrids and full-blooded Genestealers become psychically-linked to each other in a miniature version of the Tyranid Hive Mind, and become fiercely loyal to their "family". Over time, the "family" grows as its members continue to breed and bring in more members, and the "family" will eventually grow large and become a true Genestealer Cult, sometimes worshipping some vaguely defined entity which will 'deliver' the worshipers and their planet from the usual harshness of life in the Warhammer 40,000 universe.

The psychic link maintained by the "family" or the Cult - henceforth a Genestealer "brood" - acts as a potent psychic beacon, attracting the forces of the Tyranids' main Hive Fleet to their planet. As more members are brought into the group, this psychic beacon grows stronger. As shown with the events leading up to the Tyranid invasion of Ichar IV (Kelly and Chambers, 2004), a brood can eventually grow so large that it will begin conducting sabotage or causing riots intended to cause chaos and disrupt Imperial governance and defense of the afflicted planet. Broods have even been observed rebelling against Imperial authority, attempting to seize ruling power over the planet for themselves. The ultimate goal (whether the Brood consciously knows it or not) is to sow discord or even neutralize planetary defenses in order to ease the Tyranid conquest and consumption of the planet's biomass.

Although pureborn Genestealers are frequently born from other species, they are said to lack creative intelligence. They are unable to wield weapons, even those of the species from which they are born; Hybrids have some degree of intelligence and are able to make use of weapons. Genestealers do have incredible animal cunning, however - they have even been seen acting as a sort of scout for Tyranid armies, stalking ahead of the main force.


A Patriarch is the purestrain Genestealer who first originated a Brood. As the first Genestealer of the group, all other members are psychically linked through it; this allows it to attain a level of intelligence much higher than that of other Genestealers. Over time, it can become a very powerful psyker, and it grows much larger physically than an average Genestealer, becoming much stronger and more resistant to damage.

As the Tyranids approach the planet that the Patriarch calls home, it will fall under the power of the Tyranid Hive Mind, and begin leading attacks on vulnerable positions to facilitate the inevitable invasion. It is assumed that it knows nothing of its role in the Tyranid invasion, and once the Tyranids are successful, it and its Brood are also consumed by the Hive Fleet. Patriarchs are known to live for hundreds of years. They are seen by the Genestealer Cult as a "father" figure, and should the Patriarch's destruction come to pass, the Cult would be thrown into disarray. The loss of the Patriarch and its hold on the Cult would likely lead to its destruction; the sudden absence of the telepathic link from the Patriarch would lead the Hybrids and remaining purestrain Genestealers of the Cult to revert to little more than feral monsters.

Many have speculated that the Patriarch and the Broodlord are one and the same. This is mainly due to both their psychic prowess and leadership over other Genestealers. Indeed this is even hinted in an interview with a Games Workshop sculptor. However the Broodlord is statted-out as a separate sub-species of Genestealer bred solely for its superior combat prowess and synaptic leadership, while the Patriarch is simply any ancient purestrain Genestealer that leads a Genestealer Cult.


The Genestealer Reproductive Cycle, beginning with the pure Genestealer and ending with a 4th Generation Hybrid or Primacii; the Contagii, or human hosts, are not shown

A Genestealer Hybrid is created by a Genestealer implanting its DNA into a host organism. The DNA implant then slightly enhances the host's physiology, and noticeably alters their reproductive system. When infected hosts breed (it is unknown if only one or both parents need to be infected), their firstborn child will be a Genestealer Hybrid. The parents and any later children will be psychically enslaved to their Hybrid family member, cherishing it with abnormally large amounts of affection. Depending on their generation, the Hybrid offspring range from looking like purestrain Genestealers with human traits to humans with Genestealer traits; F1, F2, and F3 Hybrids reproduce asexually like purestrain Genestealers, while F4 hybrids reproduce sexually with another member of the host species. The F5 generation is born as a purestrain Genestealer once more, restarting the cycle.


Genestealer Magus

The Genestealer Magus is an F4 Hybrid that appears almost entirely human, although baldness, denser-than-normal bone structure, hypnotic blue/purple eyes, slightly bluish/purplish-tinted skin, and fangs are common traits. The Magus, unlike a purestrain Genestealer and earlier generations of Hybrids, is highly intelligent and is a powerful psyker, but is absolutely dedicated to serving the Patriarch. It uses its human appearance to act as the face of the Brood, and relays the orders of the Patriarch to the members of the Brood and the Genestealer Cult. Like the Patriarch, it presumably knows nothing of its role in the Tyranid invasion it is aiding. Magi are the exact opposite of the purestrain Genestealer, highly intelligent beings that are nonetheless extremely vulnerable in close melee combat. The firstborn child of a Magus or Hierarch (a non-psychic F4), will always be a purestrain Genestealer, but the species of any later children can be consciously chosen by the F4 parent.

Brood Brothers

Brood Brothers are those baseline humans or other host species individuals who have been infected by Genestealer DNA and have been psychically enslaved by their Hybrid offspring, often referred to by the Adeptus Mechanicus Magi Biologis as the Contagii. They revere and serve the Genestealer Patriarch and battle mindlessly on behalf of the Genestealer Cult. Their main duty is to join with the local population of the infested planet and help the Genestealer Cult to take over the world. Brood Brothers are able to enter into combat like the Imperial Guard, ally with Renegade Imperial troops, or use "liberated" vehicles once owned and operated by the local Planetary Defence Force or Imperial Guard regiments of the planet which they are infesting. They are led into battle by command squads formed of Hybrids.

Ordo Xenos Data

Ordo Xenos Departmento Analyticus Record
Designation Genestealer
Common Title Stealer, Leech, Sewerstalker, Scuttler, Clawfiend, Ghost
Species Name Corporaptor hominis (Purestrain Genestealer), Corporaptor ymgarli (Ymgarl Genestealer) , Vermis (Tyrannus) Furii (Broodlord)
Average Height 1.9 metres
Average Weight 0.3 tonnes
First Encountered Moons of Ymgarl
Role Infiltration
Threat Evaluation High

History of the Genestealers Army

Genestealers appeared in the 1st Edition of Warhammer 40,000 (Rogue Trader), but at the time were not a Tyranid species. They were simply noted as being an "enigmatic monster ... from one of the moons of Ymgarl", now "spread throughout space" and "threatening to become a real menace". Since then it has been revealed that they were the advance forces of the Tyranid invasion and are now often seen as part of a Tyranid army.

The Genestealer Cult is a substitute army that has been introduced several times for Warhammer 40,000. The initial introduction by Paul Murphy, Bryan Ansell, and Nigel Stillman was printed in White Dwarf issues 114-116 (1989). This was followed by an article from Andy Chambers and Jervis Johnson in White Dwarf issue 145 (1992) that detailed the Genestealer Cult as part of a Tyranid army. Later, Tim Huckelbery detailed the Genestealer Cult army in issues 40 and 41 (1999) of the Citadel Journal, under the title Codex: Genestealer Cults. This official supplemental Codex provided official rules for using Patriarchs, Magi, Hybrids and Broodbrother units. It even included rules for a "Transport Coven Limousine." Later, in the first Codex Tyranids, these rules were incorporated as the "Genestealer Cult Army List" and included all of the characters in their previous form sans Limousine.

In the Tyranids Codex for the 3rd Edition of Warhammer 40,000, there were no rules provided for the Genestealer Cults. With the introduction of the Broodlord in the 4th Edition, Genestealers could once again be fielded as their own army, albeit one that was restricted to HQ and Troops units only (which arguably makes it quiet ineffective). Before the 4th Edition, the 3rd Edition Genestealers were the oldest models in use to date (they were the same ones from Rogue Trader and the Space Hulk game).

There are currently two variants of the standard purestrain Genestealer: the Broodlord and the baseline Genestealer. In earlier incarnations of the Warhammer 40,000 universe, there were five separate types of Genestealers, representing the Genestealer Cult variant army, including: Genestealer Patriarchs, the Genestealer Magus, standard Genestealers, Genestealer Hybrids, and Brood Brothers.

Genestealer is also the name for the second expansion produced for the Games Workshop tabletop miniature wargame Space Hulk. The expansion is named after the Genestealers that the Space Marines battle as the primary adversaries of the game. It features psyker rules for Space Hulk.


  • Codex: Tyranids (5th Edition), pp. 15, 40, 61
  • Codex: Tyranids (4th Edition), pp. 24, 27, 39
  • Codex Imperialis, (2nd Edition), pp. 92-93
  • Dark Heresy: Creatures Anathema (RPG), pg. 90
  • Deathwatch: Ark of Lost Souls (RPG), pp. 130-132
  • Deathwatch: Mark of the Xenos (RPG), pp. 39-40
  • Deathwatch: The Emperor Protects (RPG), pp. 46-47
  • Imperial Armour Volume Four - The Anphelion Project
  • Rogue Trader: Stars of Inequity (RPG), pp. 78-79
  • Space Hulk: Mission Book (3rd Edition), pp. 46-47
  • Space Hulk: Death Angel (CCG), "Death Angel: Mission Pack 1 Expansion"
  • Warhammer 40,000: Compilation (1st Edition), pp. 88-115
  • Warhammer 40,000: Rogue Trader (1st Edition), pg. 211
  • Xenology (Background Book)
  • White Dwarf (UK) 266, "The Genestealer - Ultimate Predator"
  • White Dwarf (UK) 114, "Genestealers," by Paul Murphy, pp. 31-37
  • White Dwarf 266, "The Genestealer - Ultimate Predator" Article
  • White Dwarf 114, "Genestealers" Article
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