The Ghost of Slumber Mountain is a 1918 film written and directed by special effects pioneer Willis O'Brien, produced by Herbert M. Dawley, and starring both men. It is the first movie to show live actors and stop-motion creatures together on the screen and is often cited as a trial run for The Lost World. An advertising tagline for the film read "These giant monsters of the past are seen to breathe, to live again, to move and battle as they did at the dawn of life!". The film attracted the interest of Watterson R. Rothacker, founder of the Industrial Motion Picture Company, who was so impressed by the film's special effects, he joined forces with O'Brien to create the dinosaurs of The Lost World (1925), a classic that advanced the development of special effects techniques.