The United Planets Cruiser C-57D is a fictional starship featured in MGM's 1956 science fiction film Forbidden Planet. The design used for the starship is a flying saucer, inspired by the spate of UFO sightings during the 1950s, and which itself inspired the look of the exterior saucer section and interior design of another iconic starship, Star Trek's USS Enterprise, as well as the Jupiter 2 space craft from the original 1965 TV series Lost in Space.

Forbidden Planet is a 1956 American science fiction film from Metro-Goldwyn-Mayer, produced by Nicholas Nayfack, and directed by Fred M. Wilcox from a script by Cyril Hume that was based on an original film story by Allen Adler and Irving Block. It stars Walter Pidgeon, Anne Francis, and Leslie Nielsen. Shot in Eastmancolor and CinemaScope, it is considered one of the great science fiction films of the 1950s, a precursor of contemporary science fiction cinema. The characters and isolated setting have been compared to those in William Shakespeare's The Tempest, and the plot contains certain happenings analogous to the play, leading many to consider it a loose adaptation.