Devil's Island is a 1939 American prison film directed by William Clemens and starring Boris Karloff. This film is notable for Karloff in a then-rare sympathetic role, as opposed to his usual antagonistic characters in horror films. The plot appears to have been recycled from John Ford's The Prisoner of Shark Island, which depicted the true story of doctor Samuel Mudd, who treated the injury of John Wilkes Booth after he assassinated Lincoln.