's big scary monster.
The Genestealer was introduced in the original Warhammer 40000
in the miscellaneous scary aliens
section as a death world
creature that reproduced by implanting its egg
s in unwary creatures. After the eggs were implanted, they fertilised themselves with the host's DNA
, producing a hybrid creature. By some unexplained method, the genestealers had a 'backup copy' of the original pure DNA, and if the means to implant eggs became hybridized out, could produce a new purestrain asexually
The purestrain resembled a Giger
alien, with a sea anemone
like ring of tentacles where the jaw would be.
When Space Hulk
was released (but still before Alien 3
), the genestealer had become much more insidious. The genestealer eggs, once implanted, were not lethal, but merely brainwash
ed the host into protecting and nurturing the new hybrid. The genestealers could communicate psychicaly, and sought each other out to form a hive. Genestealer-human
hybrids became more and more intelligent with each generation, with an increasingly human appearance. From the outside, the genestealers would appear to be a secret society, or a cult, recruiting new hosts from the native population. The original genestealer, the patriarch, would control the brood, growing larger, less mobile, but with potent psychic powers. Eventually the cult would produce a magus
, a charismatic figurehead
that could pass for human under the closest scrutiny. Led by the patriarch
, the magus would take control of the the remaining uninfected hosts, and lead them to infect other cities. A genestealer infestation on a hive world
, if not spotted early, could lead to infection of hundreds of billions, and virus bombing by the imperial navy
. Typically, crack squads of space marine terminator
s would attempt to root out and kill the magus
, giving conventional forces a fighting chance of rooting out and killing
every genestealer, hybrid and brood brother on the planet.
The genestealer now had four arms - two hands, and two large claws. The overall impression was of an armoured velociraptor
, with a deformed, humanoid head. The hybrids progessively stood straighter, had shorter tails, fewer limbs, less armour.
By the release of warhammer 40000
version 2, it was revealed that the genestealers were merely the precursors of a much larger threat. The Tyranid
s, a single huge hive mind
, travelling from one galaxy to the next, and devouring everything in their path, used the genestealers to infiltrate and pacify
entire planets, removing any resistance the planet could have posed. As the hive fleet
approached, guided by the eminations of the patriarch
, the genestealer cult came under the control of the hive mind, and the entire planet (genestealers and all) was devoured.
The general appearance of the genestealer was unchanged in this revision.