Mad Monster Party? is a 1967 stop-motion animated musical comedy film produced by Rankin/Bass Productions for Embassy Pictures. The film stars the voices of Boris Karloff, Allen Swift, Gale Garnett, and Phyllis Diller. It tells the story of a mad scientist who achieves the secret of total destruction as he summons all the monsters to his island home to show it off while planning to retire as the head of the "Worldwide Organization of Monsters".

Although less well known than Rankin/Bass's holiday specials, it has become a cult film. The film is a camp homage to the classic monster movies of the 1930s-'40s. It was one of Karloff's final projects, and his last film in connection to Frankenstein.