Inseminoid (titled Horror Planet in the United States) is a 1981 science fiction horror film directed by Norman J. Warren and starring Judy Geeson, Robin Clarke and Stephanie Beacham, along with Victoria Tennant in one of her early film roles. The plot concerns a team of archaeologists and scientists who are excavating the ruins of an ancient civilisation on a distant planet. One of the women in the team (Geeson) is impregnated by an alien creature and taken over by a mysterious intelligence, driving her to murder her colleagues one by one and feed on them.

A co-production of British producer Richard Gordon and Hong Kong’s Shaw Brothers Studio, Inseminoid was written by Nick and Gloria Maley, a married couple who had been part of the special effects team on Warren's earlier film Satan's Slave. Filmed between May and June 1980 on a budget of £1 million, half of which was supplied by the Shaw Brothers, it was shot mostly on location at Chislehurst Caves in Kent as well as on the island of Gozo in Malta, combined with a week's filming at Lee International Studios in London. Composer John Scott completed the film's electronic musical score over recording sessions that lasted many hours.

Despite a good box office response in the UK and abroad, Inseminoid failed to impress most commentators, who criticised the effects and production design. The overall quality of the acting was also poorly received, although Geeson's performance was praised. Criticism was also directed at the premise involving an alien insemination, which some commentators viewed as a weak imitation of Alien (1979). Both Warren and 20th Century Fox, distributor of Alien, rejected claims that Inseminoid was influenced by this film.