Edison's Conquest of Mars

The ancient astronaut theory has a long and winding history based, in large measure, on the fertile interaction of speculative fiction and speculative history. Its roots can be traced to Victorian era pseudoscience, including Theosophy, speculation about the existence of Atlantis, and mystical investigations of the Great Pyramid of Egypt. Science fiction played its role, too. Sometimes too well.
Edison's Conquest of Mars (1898) drew on all of these themes to deliver one of earliest science fiction stories to present extraterrestrial beings as ancient astronauts. In the novel, Martians came down to the earth in prehistory, built the pyramids and the Sphinx, and abducted humans to use as slave labor-all claims suggested in the work of twentieth century ancient astronaut theorists.
Serviss' novel may not have inspired the ancient astronaut genre, but it is a fascinating example of how the ideas available in popular culture repeatedly combined to produce the same idea time and again.