Brother Rat is a 1938 American comedy drama film about cadets at Virginia Military Institute in Lexington, Virginia, directed by William Keighley, and starring Ronald Reagan, Priscilla Lane, Eddie Albert (in his film debut), Jane Wyman, and Wayne Morris.

The film is an adaptation of the successful Broadway play of the same name written by two former VMI cadets, John Monks, Jr. and Fred Finklehoffe, which ran for 577 performances between December 1936 and April 1938. Albert and supporting actor William Tracy reprised their roles from the stage productions.

After the film's production, Reagan married Wyman in 1940. The title refers to the term used for cadets in their first year at the Institute. Scenes of the film were shot on site in Lexington on the institute's historic parade ground, and the baseball game scene was filmed at Alumni Memorial Field.