Cimarron is a 1931 pre-Code epic Western film starring Richard Dix and Irene Dunne, and directed by Wesley Ruggles. Released by RKO, it won Academy Awards for Best Picture, Best Adapted Screenplay (written by Howard Estabrook and based on Edna Ferber's 1930 novel Cimarron), and Best Production Design (by Max Rée).

Both Dix and Dunne were nominated for their leading roles, and Edward Cronjager for Best Cinematography, but did not win. Estelle Taylor, Edna May Oliver, and Roscoe Ates appeared in supporting roles. Epic in scope, spanning forty years from 1889 to 1929, Cimarron was RKO's most expensive production up to that date, as well as its first production to win the Best Picture Oscar. It was a critical success, although it did not recoup its production costs during its initial run in 1931.

It is the first of four Westerns to ever win the top honor at the Academy Awards, being followed almost 60 years later by Dances with Wolves in 1990, Unforgiven in 1992, and No Country For Old Men in 2007.

Due to being a film published in 1931, it will enter the public domain on January 1, 2027.