The Aliens (Xenomorphs) are a fictional endoparasitoid extraterrestrial species that are the primary antagonists of the Alien film series and for Logan in the Logan's Adventures 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.
Unlike many other recurring enemy extraterrestrial races in science fiction, the Aliens are not an intelligent civilization, but predatory creatures with no higher goals than the propagation of their species and the destruction of life that could pose a threat. Like wasps or termites, Aliens are eusocial, with a single fertile queen breeding a caste of warriors. The Aliens' biological life cycle involves traumatic implantation of parasitic larvae inside living hosts, which mature before erupting from the host's chest. Their design deliberately evokes many sexual images, both male and female, to illustrate their blurring of human sexual dichotomy.
- The Alien design is credited to Swiss surrealist and artist H. R. Giger, originating in a lithograph called Necronom IV and refined for the series' first film, Alien. The species' design and life cycle have been extensively added to throughout each film.