Short answers, pulled from the story.
Alien was directed by Ridley Scott, who had previously made his debut feature The Duellists in 1977. Scott was brought onto the project by producers Gordon Carroll, David Giler, and Walter Hill of Brandywine Productions after several other directors, including Peter Yates, John Boorman, and Robert Altman, were considered and passed over.
Dan O'Bannon wrote the screenplay, based on a story he developed with Ronald Shusett. The Writers Guild of America awarded O'Bannon sole screenplay credit despite extensive rewrites by David Giler and Walter Hill, who added significant elements including the android character Ash.
Bolaji Badejo, a 26-year-old design student, portrayed the adult alien in most scenes. Badejo stood 6 ft 10 in tall and was discovered in a bar by a member of the casting team. Stuntmen Eddie Powell and Roy Scammell also portrayed the alien in select scenes.
Swiss artist H. R. Giger designed the alien creature and its environment, basing the work on his painting Necronom IV. Giger sculpted the adult alien's body using plasticine and incorporated snake vertebrae and Rolls-Royce cooling tubes into the design. Carlo Rambaldi manufactured the head, which contained roughly 900 moving parts; Rambaldi's original alien jaw is now on display at the Smithsonian Institution.
Alien grossed $78.9 million in the United States and £7.8 million in the United Kingdom during its first theatrical run. Its total worldwide gross has been estimated at between $109 million and $188 million. The film opened on the Memorial Day weekend of 1979 in 90 American theaters, setting 51 house records and grossing $3,527,881 in four days.
Alien won the Academy Award for Best Visual Effects, three Saturn Awards (Best Science Fiction Film, Best Direction for Ridley Scott, and Best Supporting Actress for Veronica Cartwright), a Hugo Award for Best Dramatic Presentation, and a BAFTA Award for Best Film Music for Jerry Goldsmith's score. In 2002, the Library of Congress selected it for preservation in the United States National Film Registry.