An absoulte MUST SEE for any sci-fi fan! This film helped to define the genre, with inovation in special effects and costuming, a political/humanitarian story, and an archtypical soundtrack. No one can forget those famous words: "Klaatu barada nikto"
Super bonus points for being the first film to have a theremin scored, rather than improvised for the soundtrack.
Director: Robert Wise
Main Cast: Michael Rennie, Patricia Neal, Billy Gray, Hugh Marlowe, Lock Martin
( Blasphemy! I just found out that they remade this film in 2008, with Keanu Reeves. I have nothing nice to say about that, other than "if it ain't broke, don't fix it." )