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 film to show live actors and stop-motion creatures together on the screen[2][3] 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 dawn of life."

[sic] 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.

The supplementary material includes The Ghost of Slumber Mountain in a new 2K HD restoration by the "Dinosaur Museum",[7][8] although one source lists the film's running time at less than 14 minutes.

[9] The film as presented on the Flicker Alley Blu-ray runs thirteen minutes after the opening restoration credits are finished.

[10]) Barnum Brown, the renowned dinosaur hunter who discovered Tyrannosaurus rex, was a technical advisor on the film.

Author and explorer Jack Holmes (Dawley) tells his two young nephews about an adventure he had in the woodlands around Slumber Mountain, near the Valley of Dreams.