Forbidden World, originally titled Mutant, is a 1982 American science fiction erotic horror film. The screenplay was written by Tim Curnen, from a screenstory by R.J. Robertson and Jim Wynorski. It was co-edited and directed by Allan Holzman, who had edited Battle Beyond the Stars two years earlier. The cast includes Jesse Vint, Dawn Dunlap, June Chadwick, Linden Chiles, Fox Harris and Michael Bowen. Forbidden World has also been released under the titles Mutant and Subject 20.

The film received three nominations for the 1983 Saturn Awards: Best Low Budget Film, Best Make-up and Best Special Effects. It was generally panned by critics as a cheap, exploitative imitation of the movie Alien, with sex, nudity, uneven editing, cheap special effects, and a sound design which some moviegoers found unpleasant, although the electronic music score produced by Susan Justin received mostly positive attention. It is frequently paired with and compared to the previous year's Corman-produced Alien rip-off Galaxy of Terror, with which Forbidden World shares some of the same sets (designed by James Cameron). The movie also makes use of footage recycled from the 1980 movie Battle Beyond the Stars, which was also produced by Corman.

The film was remade in 1991 under the title Dead Space, on which Corman served as executive producer. The remake has minor variations but still retains the plot and character stylings of the original, also referring to the mutated virus as a "metamorph" as the original did.