Daniel Thomas O'Bannon was an American film screenwriter, director and visual effects supervisor, usually in the science fiction and horror genres.

Alien is a 1979 science fiction horror film directed by Ridley Scott and written by Dan O'Bannon. Based on a story by O'Bannon and Ronald Shusett, it follows the crew of the commercial space tug Nostromo, who, after coming across a mysterious derelict spaceship on an uncharted planetoid, find themselves up against a deadly and aggressive extraterrestrial loose within their vessel. The film stars Tom Skerritt, Sigourney Weaver, Veronica Cartwright, Harry Dean Stanton, John Hurt, Ian Holm, and Yaphet Kotto. It was produced by Gordon Carroll, David Giler, and Walter Hill through their company Brandywine Productions and was distributed by 20th Century-Fox. Giler and Hill revised and made additions to the script; Shusett was the executive producer. The Alien and its accompanying artifacts were designed by the Swiss artist H. R. Giger, while concept artists Ron Cobb and Chris Foss designed the more human settings.