Alien 3 (styled as Alien³) is a 1992 science fiction horror film, the third installment in the Alien franchise, and the debut of director David Fincher. It is a sequel to James Cameron's Aliens.

The story begins with an ejected pod from the Colonial Marine spaceship Sulaco in Aliens crash-landing on a refinery/prison planet, killing everyone aboard except Lieutenant Ellen Ripley (Sigourney Weaver). Unknown to Ripley, an Alien egg was aboard the ship. It is born in the prison and begins a killing spree.

Alien 3 had a difficult production, with various screenwriters and directors getting involved in the project, and shooting even started without a finished script. The film was the big-budget debut of a young David Fincher, who was brought into the project very late in its development, after a proposed version written by Vincent Ward at the helm fell through. Fincher had little time to prepare, and the experience making the film proved agonizing for him, as he had to endure incessant creative interference from the studio and had to shoot the film without having a definite script. The added weight was also to create a film worthy of the work of the two revered directors that had gone before him, James Cameron and Ridley Scott. Upon completion, the studio dismantled and reworked it without Fincher's consent, including releasing a teaser trailer that suggested the film would take place on Earth.

The film was released to mixed reviews. While not very successful at the United States box office, it earned over $100 million outside of North America.