High Quality Content by WIKIPEDIA articles! The Alien (sometimes referred to as a Xenomorph) is a fictional endoparasitoid extraterrestrial species that is the primary antagonist of the Alien film series. The species made its debut in the 1979 film Alien, and reappeared in its sequels Aliens (1986), Alien 3 (1992), Alien Resurrection (1997), as well as two crossovers Alien vs. Predator (2004) and Aliens vs. Predator: Requiem (2007), and finally in Ridley Scott`s 2012 film Prometheus. It also appears in various literature and video game spin-offs from the series.