The Lunatic at Large is a 1927 American comedy film directed by Fred C. Newmeyer and starring Leon Errol, Dorothy Mackaill and Warren Cook (his final role). Written by Ralph Spence, it is based on the 1899 novel The Lunatic at Large and its sequels The Lunatic at Large Again (1922), The Lunatic Still at Large (1923), and The Lunatic In Charge (1926) by British writer J. Storer Clouston, which had previously inspired a 1921 film of the same title. The film shifted the setting from the original's London to New York. The film was released on January 2, 1927, by First National Pictures.