Alien

Alien or Aliens may mean:
* Extraterrestrial life, in scientific context
* Extraterrestrial life (popular culture)
* Alien (biology), a non-native species
* Alien (computing), a program that converts between different Linux package distribution file formats
* Alien (law), a person who is neither a native nor a citizen of the country of residence
* Alien (signifier), use in literature and criticism as the embodiment of an outside perspective or the sense of the other
* Alien (film) (1979 film), by Ridley Scott, which inspired the following related works:
** Aliens (1986 film), the sequel to the 1979 film
** Alien³ (1992 film), the third Alien movie
** Alien: Resurrection (1997 film), the fourth Alien movie
** Alien vs. Predator (2004 film), also a comic book series, novel series, and video game series
** Alien vs. Predator 2 (2007 film)
** Xenomorph (Alien), the alien creatures from the Alien movies
** Aliens (comic), a group of comic book series
* The Aliens, Roky Erickson's backing band
* Alien (game), a 1984 DOS text adventure
* Alien Technology, a maker of UHF RFID tags
* Aliens (video game), a number of video games
* Aliens (arcade game), a 1990 arcade shoot 'em up by Konami
* Aliens (album), an album by Irish celtic rock band Horslips
* Alienware Computer Corporation, a division of Dell