Genestealers are a fictional alien species from the Warhammer 40,000 universe, known for their stealth and cunning. They are part of the Tyranid race and are characterized by their elongated limbs, sharp claws, and a distinctive, elongated head. Genestealers are adept at infiltrating and subverting other species, often using their psychic abilities to manipulate and control their hosts. These creatures reproduce through a process called "genetic assimilation," where they infect a host species, leading to hybrid offspring. This allows them to spread their influence and create a loyal following, making them a significant threat to any civilization they encounter.