The Phantom Empire is a 1935 American Western serial film directed by Otto Brower and B. Reeves Eason and starring Gene Autry, Frankie Darro, and Betsy King Ross. This 12-chapter Mascot Pictures serial combined the Western, musical and science-fiction genres. The duration of the first episode is 30 minutes, while that of the rest is about 20 minutes. The serial film is about a singing cowboy who stumbles upon an ancient subterranean civilization living beneath his own ranch that becomes corrupted by unscrupulous greedy speculators from the surface. In 1940, a 70-minute feature film edited from the serial was released under the titles Radio Ranch or Men with Steel Faces. This was Gene Autry's first starring role, playing himself as a singing cowboy. It is considered to be the first science-fiction Western.

A serial film, film serial, movie serial, or chapter play, is a motion picture form popular during the first half of the 20th century, consisting of a series of short subjects exhibited in consecutive order at one theater, generally advancing weekly, until the series is completed. Usually, each serial involves a single set of characters, protagonistic and antagonistic, involved in a single story, which has been edited into chapters after the fashion of serial fiction and the episodes cannot be shown out of order or as a single or a random collection of short subjects.