An Unseen Enemy is a 1912 Biograph Company short silent film directed by D. W. Griffith, and was the first film to be made starring the actresses Lillian Gish and Dorothy Gish. A critic of the time stated that "the Gish sisters gave charming performances in this one-reel film". The film was shot in Fort Lee, New Jersey where early film studios in America's first motion picture industry were based at the beginning of the 20th century.