The Lost World is a 1925 American silent fantasy monster adventure film adapted from Arthur Conan Doyle's 1912 novel of the same name. The film was produced by First National Pictures, a major Hollywood studio at the time, and stars Wallace Beery as Professor Challenger. It was directed by Harry O. Hoyt and featured pioneering stop motion special effects by Willis O'Brien, a forerunner of his work on the original King Kong. Doyle appears in a frontispiece to the film, absent from some extant prints.