Ancient Astronauts and their technology is often promoted as the inspiration behind aspects of many ancient religions such as the vimanas of the Hindus, the flying chariots of Ezekiel as well as the gods of Mesopotamia. The most widely known proponents of these ideas are Erich von Däniken and the late Zecharia Sitchin.
However, I must also include Josef Blumrich who proposed that the biblical Ezekiel had encountered an alien spaceship in his 1973 book . It is worth noting that a decade earlier Arthur W. Orton wrote The Four-Faced Visitors of Ezekiel which was recently republished  and which offers similar ideas to Blumrich.
Before von Däniken, Harold T. Wilkins was already suggesting prehistoric extraterrestrial visitors in the 1950’s. He also wrote a couple of books about Atlantis. Not long after that, Egerton Sykes wrote some short articles for his Atlantis magazine(i) that were sympathetic to the idea of ancient astronauts.
R. Cedric Leonard is another Atlantis researcher who has written about Atlantis and ancient technology(aliens). The most recent attempt to link Atlantis with ancient astronauts is Kevin Falzon, who closely follows Sitchin while locating Atlantis in his native Malta. Richard Mooney speculated on a connection between Atlantis and ancient aliens four decades ago.
Nevertheless, the idea of visitors from other worlds is often traced back to the 18th century and the writings of Emanuel Swedenborg (1688-1772)(e), who not only argued that extraterrestrial beings had visited our planet, but that he had actually met them! Greg Little has also recently(g) credited Swedenborg as the originator of the alien visitors idea, but Jason Colavito has rubbished Little’s article(f) and traced the concept of extraterrestrial encounters back to Lucian (125-180 AD) together with a few others before Swedenborg. Colavito and Little are not ‘best friends’, so I can only conclude that Colavito simply wished to undermine Little’s credibility as a researcher.
Jason Colavito has also drawn attention(a) to an exhibition to be held in Beijing in July 2012, which purports to offer evidence of these ancient visitors, and has published(b) the official U.S. Government view on ancient astronauts. He also offers an overview of alien theories and scathingly criticises their proponents(c).
Colavito has also an interesting blog for 29/08/14 which quotes from a 1977 magazine that has an article suggesting that Jesus was an American astronaut who came back from the future, no doubt inspired by Planet of the Apes!(d)
Perhaps even more disconcerting is the results of a survey(h) carried out by Chapman University that show 20% of Americans believing in ancient astronauts!
In 2020, we had a bizarre tweet from billionaire, Elon Musk, claiming that “aliens built the pyramids”, I hope that this was tongue-in-cheek comment!
Also See: Extraterrestrials
(i) Atlantis, Volume 20, No.3, May/June 1967.