The film stars Tom Skerritt, Sigourney Weaver, Veronica Cartwright, Harry Dean Stanton, John Hurt, Ian Holm, and Yaphet Kotto.

While studying cinema at the University of Southern California, Dan O'Bannon had made a science-fiction comedy film, Dark Star, with director John Carpenter and concept artist Ron Cobb, with production beginning in late 1970.

[29][30] O'Bannon had written 29 pages of a script titled Memory, containing what would become the opening scenes of Alien: a crew of astronauts awakens to find that their voyage has been interrupted because they are receiving a signal from a mysterious planetoid.

[29][31] Though the project ultimately fell through, it introduced him to several artists whose work gave him ideas for his science-fiction story including Chris Foss, H. R. Giger, and Jean "Moebius" Giraud.

[30] He has also cited as influences Strange Relations by Philip José Farmer (1960), which covers alien reproduction and various EC Comics horror titles carrying stories in which monsters eat their way out of people.

[29] Hill and Giler did add some substantial elements to the story, including the android character Ash, which O'Bannon felt was an unnecessary subplot[22] but which Shusett later described as "one of the best things in the movie...That whole idea and scenario was theirs.

"[29] Hill and Giler went through eight drafts of the script in total, concentrating largely on the Ash subplot, but also making the dialogue more natural and trimming some sequences set on the alien planetoid.

Tom Skerritt, the captain, was 46, Hurt was 39 but looked older, Holm was 48, Harry Dean Stanton was 53, Yaphet Kotto was 42, and only Veronica Cartwright at 30 and Weaver at 28 were in the age range of the usual thriller cast.

Many recent action pictures have improbably young actors cast as key roles or sidekicks, but by skewing older, Alien achieves a certain texture without even making a point of it: These are not adventurers but workers, hired by a company to return 20 million tons of ore to Earth.

[26] Art director Les Dilley created 1⁄24-scale miniatures of the planetoid's surface and derelict spacecraft based on Giger's designs, then made moulds and casts and scaled them up as diagrams for the wood and fiberglass forms of the sets.

[11] Tons of sand, plaster, fiberglass, rock, and gravel were shipped into the studio to sculpt a desert landscape for the planetoid's surface, which the actors would walk across wearing space-suit costumes.

"[61] The footage was included with other deleted scenes as a special feature on the Laserdisc release of Alien, and a shortened version of it was reinserted into the 2003 Director's Cut, which was re-released in theaters and on DVD.

[70] O'Bannon introduced Scott to the artwork of H. R. Giger; both of them felt that his painting Necronom IV was the type of representation they wanted for the film's antagonist and began asking the studio to hire him as a designer.

Art director Roger Christian used scrap metal and parts to create set pieces and props to save money, a technique he employed while working on Star Wars.

[59] Special-effects supervisors Brian Johnson and Nick Allder made many of the set pieces and props function, including moving chairs, computer monitors, motion trackers and flamethrowers.

Scott described the set as the cockpit or driving deck of the mysterious ship, and the production team convinced the studio that the scene was important to impress the audience and make them aware that this was not a B movie.

[59][72] To save money, only one wall of the set was created, and the "space jockey" sat atop a disc that could be rotated to facilitate shots from different angles in relation to the actors.

The first consisted of rapidly changing still images set to some of Jerry Goldsmith's electronic music from Logan's Run, with the tagline in both the trailer and on the teaser poster "A word of warning...".

[93][95] The film had no formal premiere, yet moviegoers lined up for blocks to see it at Grauman's Egyptian Theatre in Hollywood, where a number of models, sets, and props were displayed outside to promote it during its first run.

"[112] Alien won the 1980 Academy Award for Best Visual Effects and was also nominated for Best Art Direction (for Michael Seymour, Leslie Dilley, Roger Christian, and Ian Whittaker).

Much of Alien's effectiveness as a work of horror has been attributed to its indulgence in abject themes and imagery and has thus functioned as a major framework for critics, such as Barbara Creed, in their analysis of the film.

[147] Rick Sanchez of IGN has noted the "striking resemblance"[148] between the two movies, especially in a celebrated sequence in which the crew discovers a ruin containing the skeletal remains of long-dead giant beings, and in the design and shots of the ship itself.

[149] Robert Monell, on the DVD Maniacs website, observed that much of the conceptual design and some specific imagery in Alien "undoubtedly owes a great debt" to Bava's film.

"[152] Writer David McIntee, as well as reviewers for PopMatters and Den of Geek, have noted similarities to the Doctor Who serial The Ark in Space (1975), in which an insectoid queen alien lays larvae inside humans which later eat their way out, a life cycle inspired by that of the ichneumon wasp.

The study discusses memories of Alien in the cinema and on home video from the point of view of everyday audiences, describing how many fans share the film with their children and the shocking impact of the "chestburster" scene, among other things.

Roger Ebert reiterated Gene Siskel's earlier opinion, stating that the film was "basically just an intergalactic haunted house thriller set inside a spaceship".

[clarification needed] Frederick S. Clarke, the Cinefantastique editor, wrote that Alien was "an exercise in style, refreshingly adult in approach, wickedly grim and perverse, that manages to compensate for a lack of depth in both story and characters".

"[172] David Edelstein wrote, "Alien remains the key text in the 'body horror' subgenre that flowered (or, depending on your viewpoint, festered) in the seventies, and Giger's designs covered all possible avenues of anxiety.

[180] Notably, at Paisley Abbey, during a restoration project that took place in the 1990s, a stonemason from Edinburgh hired to replace twelve crumbling stone gargoyles erected one bearing a strong resemblance to the space creature from the film.

[193] Separate from the base game's story, two downloadable content packs titled Crew Expendable and Last Survivor depict alternate versions of key events from the film, with the original cast members Sigourney Weaver, Tom Skerrit, Veronica Cartwright, Harry Dean Stanton, and Yaphet Kotto reprising their respective roles.