The Mysterious Rider is a 1938 American Western film directed by Lesley Selander and starring Douglass Dumbrille, Sidney Toler, and Russell Hayden. Written by Maurice Geraghty based on the 1921 novel The Mysterious Rider by Zane Gray, the film is about a notorious outlaw who returns to the ranch he once owned and takes a job disguised as a ranch hand. Unrecognized by the ranch's current owner, he waits patiently for an opportunity to expose the men who murdered his partner twenty years ago, framed him for the crime, and then stole his ranch. The film was later released for television in the United States as Mark of the Avenger.