Lifeforce is a 1985 British science fiction horror film directed by Tobe Hooper, adapted by Dan O'Bannon and Don Jakoby, and starring Steve Railsback, Peter Firth, Frank Finlay, and Mathilda May. Based on Colin Wilson's 1976 novel The Space Vampires, the film portrays the events that unfold after a trio of humanoids in a state of suspended animation are brought to Earth after being discovered in the hold of an alien space ship by the crew of a European Space Shuttle.

Two cuts of Lifeforce were released: a 116-minute "international cut", and a 101-minute cut ordered by American distributor Tri-Star Pictures for the film's theatrical release in the United States. Lifeforce received generally negative reviews and was a box office failure, but has since become a cult film.