Species

Species is a trilogy of sci-fi/horror films, in which scientists receive an alien transmission containing a fully-mapped out genetic code. For... reasons... they use this information and splice it with the human gene-map to engineer a half-human half-alien girl. Who promptly hits puberty, transforms into a violent, super-strong, Giger-esque shapeshifting succubus, and escapes to try and mate with suitable human men in order to produce more of her kind to wipe out and replace humanity.

West End Games released a World of Species sourcebook for its Masterbook role-playing game system, allowing players to run games set in the Species verse, which is why this article is here.