The Mad Genius (1931) is an American pre-Code drama film produced and distributed by Warner Bros. and directed by Michael Curtiz. The film stars John Barrymore, Marian Marsh, Donald Cook, Charles Butterworth, and in small roles, Boris Karloff and Frankie Darro. The film is based on the play The Idol (1929) by Martin Brown, which opened in Great Neck, Long Island but never opened on Broadway.