The Beast in the Cellar is a 1971 British horror film written and directed by James Kelly and starring Beryl Reid and Flora Robson. The film was produced by Leander Films and Tigon British Film Productions.

Beryl Elizabeth Reid was a British actress. She won the 1967 Tony Award for Best Actress in a Play for The Killing of Sister George, the 1980 Olivier Award for Best Comedy Performance for Born in the Gardens, and the 1982 BAFTA TV Award for Best Actress for Smiley's People. Her film appearances included The Belles of St. Trinian's (1954), The Killing of Sister George (1968), The Assassination Bureau (1969), and No Sex Please, We're British (1973).