Some writers have proposed that intelligent extraterrestrial beings have visited Earth in antiquity or prehistory and made contact with humans. Such visitors are called ancient astronauts or ancient aliens. Proponents suggest that this contact influenced the development of human cultures, technologies and religions. A common variant of the idea is that deities from most, if not all, religions are actually extraterrestrials, and their advanced technologies were wrongly understood by primitive men as evidence of their divine status.
These proposals have been popularized, particularly in the latter half of the 20th century, by writers such as Erich von Däniken, Giorgio A. Tsoukalos, Zecharia Sitchin, Robert K. G. Temple, David Icke and Peter Kolosimo, but the idea that ancient astronauts actually existed is not taken seriously by most academics, and has received little or no credible attention in peer reviewed studies. Ancient astronauts have been widely used as a plot device in science fiction.