The Sky Ranger (aka The Man Who Stole the Moon) is a 1921 American 15-episode/chapter silent film serial.

Professor Elliott has made a number of important inventions, including developing a fast, silent aircraft.

His latest work concerns a new, powerful light, which is the object of those criminals who want to steal the invention.

The Sky Ranger was not to be confused on the 1928 short film based on the popular "Russ Farrell" magazine stories and the film series, Russ Farrell, Aviator that stars Reed Howes as the dashing, devil-may-care flyboy hero.

[5] The new title was a way to market the production as more of a science fiction film, capitalizing on interest in this genre.