The Great Sinner is a 1949 American film noir drama film directed by Robert Siodmak. Based on the 1866 short novel The Gambler written by Fyodor Dostoyevsky, the film stars Gregory Peck, Ava Gardner, Frank Morgan, Ethel Barrymore, Walter Huston, Agnes Moorehead and Melvyn Douglas.

Robert Siodmak was a German film director who also worked in the United States. He is best remembered as a thriller specialist and for a series of films noir he made in the 1940s, such as The Killers (1946).