Planet of the Vampires (Italian: Terrore nello spazio, lit. 'Terror in Space') is a 1965 science fiction horror film produced by Fulvio Lucisano, directed by Mario Bava, that stars Barry Sullivan and Norma Bengell. The screenplay, by Bava, Alberto Bevilacqua, Callisto Cosulich, Antonio Roman and Rafael J. Salvia, was based on an Italian-language science fiction short story, Renato Pestriniero's "One Night of 21 Hours". American International Pictures released the film as the supporting film on a double feature with Daniel Haller's Die, Monster, Die! (1965).

In the United States, it was released under the title "Planet of the Vampires," while in the UK, it was released as "The Demon Planet"

The story follows the horrific experiences of the crew members of two giant spaceships that have crash landed on a forbidding, unexplored planet. The disembodied inhabitants of the world possess the bodies of the crew who died during the crash, and use the animated corpses to stalk and kill the remaining survivors.

The film was co-produced by AIP and Italian International Film, with some financing provided by Spain's Castilla Cooperativa Cinematográfica. Ib Melchior and Louis M. Heyward are credited with the script for the AIP English-language release version. Years after its release, some critics have suggested that Bava's film was a major influence on Ridley Scott's Alien (1979) and Prometheus (2012), in both narrative details and visual design.