Night Must Fall is a 1937 American film adaptation of the 1935 play by Emlyn Williams, adapted by John Van Druten and directed by Richard Thorpe. It stars Robert Montgomery, Rosalind Russell and Dame May Whitty in her Hollywood film debut at age 72, who earned an Academy Award nomination for Best Supporting Actress. She reprised her role in the stage drama in London and New York City. A critical success, Night Must Fall was named the best film of the year by the National Board of Review. Robert Montgomery also received an Oscar nomination for Best Actor in a Leading Role. A 1964 remake starred Albert Finney, although the remake did not do as well as the original.

Night Must Fall is a play, a psychological thriller, by Emlyn Williams, first performed in 1935. There have been three filmed adaptations: Night Must Fall (1937); a 1954 adaptation on the television anthology series Ponds Theater starring Terry Kilburn, Una O'Connor, and Evelyn Varden; and Night Must Fall (1964).