Alien 3 (stylized as Alien³) is a 1992 American science fiction horror film directed by David Fincher and written by David Giler, Walter Hill, and Larry Ferguson, from a story by Vincent Ward. It stars Sigourney Weaver, reprising her role as Ellen Ripley. It is the third instalment of the Alien franchise and led to a sequel, Alien Resurrection (1997).

Set immediately after the events of Aliens (1986), Ripley and an Alien organism are the only survivors of the Colonial Marine spaceship Sulaco following an escape pod's crash on a planet housing a penal colony populated by violent male inmates. Additional roles are played by Charles Dance, Brian Glover, Charles S. Dutton, Ralph Brown, Paul McGann, Danny Webb, Lance Henriksen, Holt McCallany, Pete Postlethwaite, and Danielle Edmond.

The film faced problems during production, including shooting without a script and the attachment of various screenwriters and directors. Fincher, in his feature directorial debut, was brought in to direct after a proposed version with Ward as director was cancelled during pre-production.

Alien 3 was released on May 22, 1992. While it underperformed at the American box office, it earned over $100 million outside North America. The film received mixed reviews and was regarded as inferior to previous instalments. Fincher has since disowned the film, citing studio interference and deadlines. It was nominated for an Academy Award for Best Visual Effects, seven Saturn Awards (Best Science Fiction Film, Best Actress for Weaver, Best Supporting Actor for Dutton, Best Direction for Fincher, and Best Writing for Giler, Hill, and Ferguson), a Hugo Award for Best Dramatic Presentation, and an MTV Movie Award for Best Action Sequence. In 2003, a revised version of the film known as the Assembly Cut was released without Fincher's involvement, which received a warmer reception.