Alien is a 1979 American science-fiction horror film directed by Ridley Scott, and starring Tom Skerritt, Sigourney Weaver, Veronica Cartwright, Harry Dean Stanton, John Hurt, Ian Holm and Yaphet Kotto. The film's title refers to a highly aggressive extraterrestrial creature that stalks and kills the crew of a spaceship. Dan O'Bannon wrote the screenplay from a story he wrote with Ronald Shusett, drawing influence from previous works of science fiction and horror. The film was produced by Gordon Carroll, David Giler and Walter Hill through their Brandywine Productions and distributed by 20th Century Fox. Giler and Hill made revisions and additions to the script. Shusett was executive producer. The eponymous Alien and its accompanying elements were designed by Swiss surrealist artist H. R. Giger, while concept artists Ron Cobb and Chris Foss designed the human aspects of the film. Alien was the first film produced in the Alien franchise and is the second chronologically, with the 2012 film Prometheus set in an earlier timeframe.
Alien received both critical acclaim and box office success, receiving an Academy Award for Best Visual Effects, Saturn Awards for Best Science Fiction Film, Best Direction for Scott, and Best Supporting Actress for Cartwright, and a Hugo Award for Best Dramatic Presentation, along with numerous other award nominations. It has remained highly praised in subsequent decades, being considered one of the greatest films of all time. In 2002 the film was deemed "culturally, historically or aesthetically significant" by the Library of Congress and was selected for preservation in the United States National Film Registry.  In 2008, it was ranked as the seventh-best film in the science fiction genre by the American Film Institute, and as the 33rd greatest film of all time by Empire magazine.
The success of Alien spawned a media franchise of novels, comic books, video games, and toys. It also launched Weaver's acting career by providing her with her first lead role, and the story of her character Ripley's encounters with the Alien creatures became the thematic thread that ran through the sequels Aliens (1986), Alien 3 (1992) and Alien: Resurrection (1997). A fourth sequel is under development.