Alien primarily refers to:

• Alien (law), a person in a country who is not a national of that country
  • Enemy alien, the above in times of war
• Extraterrestrial life, life which does not originate from Earth
  • Specifically, a lifeform with extraterrestrial intelligence
  • For fictional extraterrestrial life, see Extraterrestrials in fiction
• Introduced species, a species not native to its environment

Alien(s), or The Alien(s) may also refer to:

• AliEn (ALICE Environment), a grid framework
• Alien (file converter), a Linux program
• Alien Technology, a manufacturer of RFID technology

• Alien (franchise), a media franchise
  • Xenomorph, the titular alien in the franchise

• Alien (film), a 1979 film by Ridley Scott
  • Aliens (film), second film in the franchise from 1986 by James Cameron
  • Alien 3, third film in the franchise from 1992 by David Fincher
  • Alien Resurrection, fourth film in the franchise from 1997 by Jean-Pierre Jeunet
  • Alien vs. Predator (film), fifth film in the franchise from 2004 by Paul W. S. Anderson
  • Aliens vs. Predator: Requiem, sixth film in the franchise from 2007 by the Brothers Strause
  • Prometheus (2012 film), seventh film in the franchise from 2012 by Ridley Scott
  • Alien: Covenant, eighth film in the franchise from 2017 by Ridley Scott
  • Alien: Romulus, ninth film in the franchise from 2024 by Fede Álvarez
• Alien 2: On Earth, a 1980 unofficial sequel of the 1979 Alien film
• Alien Visitor (also titled Epsilon) (1995 film) Australian–Italian science fiction film by Rolf de Heer
• The Alien (2016 film), a 2016 Mexican film
• The Alien (unproduced film), an incomplete 1960s Indian–American film
• Alienoid, a 2022 South Korean film

• Alien novels, an extension of the Alien franchise
• Aliens: Colonial Marines Technical Manual, a 1995 book by Lee Brimmicombe-Wood, a guide to the fictional United States Colonial Marines
• Aliens (Tappan Wright novel), a 1902 novel by Mary Tappan Wright
• Aliens! (anthology) a 1980 anthology of science fiction edited by Gardner Dozois and Jack Dann
• The Alien (novel), the eighth book in the Animorphs series by Katherine Applegate
• The Aliens (play), a 2010 play by Annie Baker

• Alien (band), a 1980s Swedish rock group
• The Aliens (Australian band), a 1970s new wave group
• The Aliens (Scottish band), a 2005–2008 rock group
• The Aliens, the backing band for the American musician Jared Louche on his 1999 solo debut album Covergirl

• Alien (soundtrack), 1979
• Alien (Beam album), 2022
• Alien (Northlane album), 2019
• Alien (Strapping Young Lad album), 2005
• Alien, a 1989 EP by Tankard
• Aliens (soundtrack), 1987

• "Alien" (Britney Spears song), 2013
• "Alien" (Jonas Blue and Sabrina Carpenter song), 2018
• "Alien", a song by Atlanta Rhythm from the album Quinella, 1981
• "Alien", a song by Bush from the album Sixteen Stone, 1994
• "Alien", a song by Dead Letter Circus from the EP Dead Letter Circus, 2007
• "Alien", a song by The Devil Wears Prada from the EP Space, 2014
• "Alien", a song by Erasure from the album Loveboat, 2000
• "Alien", a song by Japan from the album Quiet Life, 1979
• "Alien", a song by Lamb from the album Fear of Fours, 1999
• "Alien", a song by Nerina Pallot from the album Dear Frustrated Superstar, 2001
• "Alien", a song by P-Model from the album Landsale, 1980
• "Alien", a song by Pennywise from the album Straight Ahead, 1999
• "Alien", a song by Stray Kids from the album SKZ-Replay, 2022
• "Alien", a song by Structures from the album Life Through a Window, 2014
• "Alien", a song by the National from the album First Two Pages of Frankenstein, 2023
• "Alien", a song by Third Day from the album Conspiracy No. 5, 1997
• "Alien", a song by Thriving Ivory from the album Thriving Ivory, 2003
• "Alien", a song by Tokio Hotel from the album Humanoid, 2009
• "Alien", a 2018 song by Beach House
• "Alien", a 2020 song by Lee Su-hyun
• "Alien", a 2020 song by Dennis Lloyd
• "Aliens" (song), a 2017 song by Coldplay
• "Aliens", a 1984 song by Warlord
• "The Alien", a song by Dream Theater from the album A View from the Top of the World, 2021

• Alien (1982 video game), a 1982 maze game based on the 1979 film
  • Alien (1984 video game), based on the film
  • Aliens (1990 video game), a game by Konami, based on the sequel of the film
  • Alien: Isolation, a 2014 video game based on the Alien science fiction horror film series
  • See also: List of Alien, Predator, and Alien vs. Predator games
• Aliens (1982 video game), a text-only clone of Space Invaders written for the CP/M operating system on the Kaypro computer

• Alien (Armenian TV series), a 2017 melodrama series
• Alien: Isolation – The Digital Series, web series in the Alien franchise from 2019 by Fabien Dubois
  • Alien: Earth, an upcoming science fiction horror television series in the franchise by Noah Hawley
• Alien (sculpture), a 2012 work by David Breuer-Weil, in Mottisfont, Hampshire, England
• Aliens (Dark Horse Comics line)
• The Aliens (TV series), 2016 British sci-fi television series
• "Aliens" (Roseanne), a 1992 television episode

• Alien (shipping company), a Russian company
• Alien Sun (born 1974), Singaporean actress
• Alien, a perfume by Thierry Mugler
• Alian District (Alien), in Taiwan

• Alians, an Islamic order
• Alien Project (disambiguation)
• Alien 4 (disambiguation)
• Alien vs. Predator (disambiguation)
• Astrobiology, the study of hypothetical alien life
• ATLiens, a 1996 album by OutKast
• Predator (disambiguation)
• UFO (disambiguation)
• Unidentified flying object (disambiguation)
• Outsider (disambiguation)
• All pages with titles beginning with Alien
• All pages with titles containing Alien