The Genestealer – genus Corporaptor Hominis – is a vanguard organism of the Tyranid race that excels at infiltration of other species’ settled worlds.
First encountered sixty years ago on the moon of Ymgarl, the Genestealer menace has travelled across the length and breadth of the Imperium, seeding themselves onto human worlds and subverting their populations. 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
Genestealers reproduce by locating a suitable host and utilizing ovipositor organs to deposit infectious DNA into the target’s systems. This genetic material attacks the somatic and germ line cells of the host and takes complete control of its reproductive systems. Several hours later, the infected victim wakes up from the incident with no wounds or any recollection of what transpired.
The fresh host will go on about its normal life and eventually reproduce with another member of its species, thus siring or giving birth to a hybrid. Due to complex pheromones and genetic reconditioning, the host and their mate will do all in their power to care for their new spawn.
The Genestealer’s reproductive cycle is truly cyclical, as a fourth-level hybrid will always spawn another purestrain Genestealer – one with a genome identical to that of the original Genestealer that began the chain.