In The Lore Explainer, we take a deep look at the lore behind our favorite games, movies, and books, and talk about the story behind them and sum up what you need to know and how you can find out more. Today we’re talking about the lore behind Genestealer Cults.

Welcome back, traveler, to the Lore Explainer. Come in from the cold, sit, and warm your bones by the fire while I tell you a story about an insidious terror lurking in the dark, roiling just below the surface of the world you know, slipping its questing tendrils through the cracks, manipulating and corrupting everything it grasps. I am referring, of course, to the Genestealer Cults.

So you’ve seen the Genestealer Cults around, going by their models you might think that they’re mostly weird bald guys and gals in hazmat space suits with prodigious forehead ridges, and now you’re wondering “So how does this all work, anyway? These guys are clearly fishy looking, how come the Inquisition doesn’t just round up all the creepy looking bald guys with rather unusual foreheads?” Well, my friend, you’ve encountered a situation where the lore and the game are somewhat separate, the Genestealer Cults are far more insidious and difficult to spot than their models might suggest.

Notes: Genestealer Cults are one of the oldest factions in Warhammer 40,000, with roots dating all the way back to the Rogue Trader days. The faction first appeared in June 1989 in White Dwarf issue 114 as part of a three-part series introducing Genestealers. This article details how Genestealers can keep a human in thrall and even outlines the first, second, third, and fourth generations of the cult in ways that are pretty much identical to modern lore. They saw a minor update in the Codex Imperialis rules that released with 2nd edition 40k – that edition’s version of Indexes – and then weren’t seen again until late 7th edition, when they resurfaced in the Deathwatch Overkill boxed set alongside updated Deathwatch models.

Down In The Darkness

A Genestealer Cult is born when a vanguard Tyranid bioform known, unsurprisingly, as a Genestealer stows away on an unwitting imperial freighter and finds its way onto a human world undetected. These are truly horrifying creatures, designed by the hive-mind both for vicious combat and preternatural stealth, and so the ‘stealer sets about secreting themselves away in the silent darkness that is so widespread beneath human settlements. Once so established, a Genestealer can begin the next stage of its foul work. A Genestealer will find its first victim by chance, perhaps a lone maintenance worker or vagrant seeking refuge in the tunnels the monster has chosen as its lair. The victim may happen to notice two shining eyes glowing in the dark before they are utterly hypnotised and rendered passive, immobile, and unaware. Through a process rather euphemistically described as a “kiss”, a Xenomor-, uh, I mean, a Genestealer extends its sharp tongue and passes into its host a packet of its own genetic material. Yikes. The Genestealer exerts its will psychically, allowing the organism to dominate the mind of their victim, subtly directing their actions from then on. Hours later the victim wakes up, with no recollection of what happened during that lost time, nor with any knowledge of the infection they now carry within them¹.

As a result of this mysterious trauma, the infected, known as Contagii, return to human society with a powerful urge to find a partner and procreate. In your typical hive city, the bottom tier of human society can’t afford to be too picky, and after knocking boots with a Contagus, their new partner receives a packet of Genestealer DNA, turning them into another Contagus, the pair becoming both psychically bonded to the original Genestealer and the most ardent pro-natalists you’ve ever seen.

Thus, the cult experiences its genesis, and growth necessarily cascades exponentially from there as the first Contagii lure other hapless victims to the Genestealer to become Contagii themselves. “Hello, colleague, I found something cool in this tunnel, come and see, do not bring weapons.”

¹ It was the 80s, you could write stuff like that without people going “hang on. What??”

The Generation Game

Eventually the burning reproductive desire of the victims begins to bear its curséd fruit, and the First Generation Hybrids are born. These creatures are twisted and deformed, their fingers ending in razorsharp claws, their heads bulbous and veiny, and often with more than the usual number of arms, characteristics that most closely resemble the original Genestealer, now styled as the cult Patriarch, ensconced in his lair. Though ordinary humans would view such offspring with revulsion, the psychic domination of the Patriarch ensures that the parents are utterly devoted to their new bundles of joy, raising them in secret to serve the will of their overlord. The First Generation Hybrids are vicious fighters but not… intellectually gifted, they are able to reproduce however, with one another and with Contagii, their children becoming the Second Generation Hybrids. These offspring are somewhat more human than their bestial forebears, although they’re still not able to hide the manifestation of their alien DNA, third arms, claws, and bulbous heads, the gang is all here.

Onward and onward the cult’s progression grows, their numbers swelling exponentially as more Hybrids are born and still more hive residents find themselves looking at a pair of glowing eyes in the dark or knocking boots with a Contagii. The Third Generation Hybrids are mostly human in their makeup and aspect, looking odd in a sort of HP Lovecraft Welcome to Innsmouth kind of way, but human enough to leave the lair with the Contagii and infiltrate society by getting jobs in mines and factories and so on. These are the baldies we know and love, the Neophyte Hybrids. At this point, calling it a “cult” is a bit like calling the Catholic Church a cult, since they might already have complete control of billions of members.

The next tier, the Fourth Generation Hybrids, are the purest manifestation of the insidiousness of a Genestealer Cult, appearing as regular unaltered humans. These hybrids are capable of moving through every part of Imperial society without raising any eyebrows. Along with many better-looking Neophytes, the highest ranking of the cult’s membership are also drawn from this generation, including specialised hybrid classifications such as Magii, Primuses, Biophagii, Clamavii, Kelermorphs, Locii, Nexii, and Sanctii.

Notes: It’s here that “The Game”‘s desire for visually distinct models and the letter of The Lore come into conflict, as obviously when you look at the in-game models, none of them look particularly “pass for a regular human person” inconspicuous. You’d notice if you were walking down the street and a tall, bald woman with prominent ridges on her forehead were strolling the other way.

The Special Children

There are a bunch of different special children in the Fourth Generation, all with particular roles within the cult’s machinery.

• Magus – The cult’s second-in-command, spiritual leaders, and chief ambassadors. Magii are born after the Genestealer DNA finds its way into a latent psyker, this potent genetic cocktail supercharges the psychic ability of the child. This potency, combined with innate natural charisma, makes a Magus the perfect public face for their movement, schmoozing with the planetary elite while the monstrous patriarch chills out in the shadows. Through this infiltration, a skilled Magus can create an atmosphere of legitimacy, appearing as the leader of a sanctioned religious or political movement. Through this access to the upper echelons of society, the cult is able to expand its influence dramatically, placing its agents inside the Administratum, the nobility, and even the Planetary Defence Forces.
• Primus – Where the Magus is a leader in diplomacy, the cult Primus is a warleader without peer. Remaining in the shadows until the critical moment, his task is to see to the military preparation and armament of the group, overseeing the theft of vehicles, arms, and materiel. When the Day of Ascenscion is at hand, the Primuses leave the shadows and leads his kin to open war, using Needle Pistols, Toxic Claws, and Xenobiotic Boneswords to wreak havoc on their foes.
• Biophagus – Your typical Mad Scientist type, the Biophagii research new ways to spread the cult’s genetic infection to new populations. Posing as Medicae in slums, or as specialists in food or medicine factories, they secretly carry out experiments on the populace, using their newfound data to taint batches of comestibles, tamper with medicine, and inject the unfortunate with concoctions of their own creation, creating swathes of new Contagii every time.
• Clamavus – Sort of cyberpunk information whizzes and propagandists par excellence, Clamavii do some Hack The Mainframe, Max Headroom shit in order to spread their cult’s ideology through the airwaves, to help them achieve this task they draw upon their natural skills at oratory. When the day of ascension finally arrives, they act by jacking into vox traffic, spreading disinformation and sowing confusion among those who stand to oppose the Cult’s menacing advance.
• Kelermorph – A regular three-armed Clint Eastwood, a Kelermorph is a legendary gunslinger that inspires fear in the cult’s enemies and fervour in the cult’s membership. These specialised lifeforms are the result of a genetic refinement that seeks to exploit the human psyche itself, by creating an irresistible heroic figure around which cultists can rally. A Kelermorph also possesses a broad spectral sensory palate, able to use it’s pistols like John Wick, only even better at shooting than Keanu himself.
• Locus – A Locus is a bodyguard par excellence for the Maguses of the cult, standing off to one side, robed and hooded but ready to flip out and go all Jet Li at a moment’s notice. In addition to their mad combat abilities, these individuals have more tricks up their sleeves, including being walking psychic amplifiers for their Maguses, and giving people migraines somehow.
• Nexos – You know how every spy or crime film has that guy, you know the one, a genius, never leaves his room/command centre, and is always on the computer? The Nexos is a bit like that but instead of leading a raid in World of Warcraft, he’s directing the cult’s armies around the battlefield like the world’s best Total War afficionado. Nexoses (Nexii?) have an incredible ability bestowed upon them by their Patriarch’s gifts, if they lay hands upon another member of the cult, they can absorb every single memory of their lives, curating a mental database so incredibly vast the CIA would bite of your hand to get their paws on.
• Sanctus – A Sanctus is a problem solver for the cult’s leadership, the problem being “this person is interfering with the cult’s operations” and the solution? Well, killing them, obviously. When you have an inhuman super-hammer at your disposal, every problem looks like a nail. A Sanctus stalks the darkness carrying xenoform bio-blades grown by the patriarch in his lair. These blades are imbued with the spirits of deceased cult members and infused with alien matter, so if you get stuck with one of these blades, or even suffer a light cut, you’re in real trouble. It’s like a Morghul knife, except rather than just suffering a horrendous poisoned wound, you also have millions of agonised voices explode into your head, which typically overloads the victim’s brain and causes them to drop dead right then and there.

Everybody’s Gone to the Rapture

While the cult works very hard at expanding their influence and membership, their goals begin to subtly shift. Motivated by the psychic domination of their Patriarch they whisper to one another of the Day of Ascension, that glorious time when the Star Children will come from the heavens and bring the cult into the blissful light for good.
In a twist that should come as no surprise to anyone that’s been paying attention, these “Star Children” are actually… A very hungry Tyranid Hive-Fleet looking for dinner. You see, since all the cultists are psychic to some degree or other, their massive numbers combine to make a big old psychic beacon that rings the dinner-bell loud and clear through the heavens.

It’s time, folks! Oh god, it’s time, at last!

Alas, biomass is biomass, and so no matter how helpful they’ve been, it’s time for dessert.

Imperial Discovery

The Imperium had known about Genestealers for a long time but the threat of cults wasn’t really on their radar until a cult was discovered on Ghosar Quintus by Chaplain Cassius and his Deathwatch Kill Team. While investigating the disappearance of Inquisitor Chaegryn the kill team came across the Cult of the Four-Armed Emperor, a sect of Genestealer Cultists whose jam is increasing their world’s industrial output to the point where they get recruited by organizations all over the place – then they use their new power to move cultists and genestealers around.

This is pretty much the conflict outlined in Deathwatch: Overkill and leads to Cassius’ personal crusade to wipe out the cult forces. It also marks the notion that rooting out and eliminating Genestealer Cults is a primary function of the Deathwatch, and they’ll be pitted against GSC on a regular basis in the lore.

Final Thoughts and Notes

The Genestealer Cults are a bit of an odd beast in Warhammer 40,000, and for a long time didn’t receive rules because they were difficult to imagine as a fully fleshed-out faction. And this is evident in their initial rules release as well, in which they relied heavily on Imperial Guard units to build a proper fighting force, with Leman Russ tanks and guard troops supporting acolyte and neophyte hybrids. The army’s 8th edition update changed things dramatically however, adding a host of new characters and vehicles like the Goliath Rockgrinder and Achilles Ridgerunner, giving the faction its own, much stronger mechanical identity and introducing blip tokens.

As an army, they’re much more mechanically defined these days, with their own mechanics and play style that appeal to more cerebral or tricky players. The faction no longer relies heavily on Astra Militarum units, and instead has a much different flavor based around ambush tactics and a never-ending supply of rank-and-file cultists.

With 10th edition focusing more on a new invasion from Hive Fleet Leviathan on the eastern galactic fringe, Genestealer Cults are more relevant than ever. They’ve infiltrated nearly every part of Imperial society, and each planet the hive fleet reaches will likely have to put down some kind of rebellion from within before it can face the invaders without. It’s a bad time to be caught in the middle.

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