Frontier Marshal is a 1934 American Pre-Code Western film directed by Lewis Seiler and starring George O'Brien. Produced by Fox Film and Sol M. Wurtzel, the film is the first based on Stuart N. Lake's enormously popular but largely fictitious "biography" of Wyatt Earp, Wyatt Earp: Frontier Marshal. A second version of the film, also produced by Wurtzel, was made in 1939, and a third interpretation by John Ford entitled My Darling Clementine was released in 1946.

He supposedly wrote the book with Earp's input, and it portrays Earp as a fearless lawman. But before the first movie was released, his widow Josephine Earp sued 20th Century Fox for $50,000 in an attempt to keep them from making the film. She said it was an "unauthorized portrayal" of Wyatt Earp. She succeeded in getting Earp's name completely excised from the movie. His character was renamed "Michael Wyatt," and the movie was released as Frontier Marshal.