The Mouse That Roared is a 1959 British satirical Eastman Color comedy film based on Leonard Wibberley's novel The Mouse That Roared (1955). It stars Peter Sellers in three roles: Duchess Gloriana XII; Count Rupert Mountjoy, the Prime Minister; and Tully Bascomb, the military leader; and co-stars Jean Seberg. The film was directed by Jack Arnold, and the screenplay was written by Roger MacDougall and Stanley Mann.