An extraterrestrial or alien is any extraterrestrial lifeform; a lifeform that did not originate on Earth. The word extraterrestrial means "outside Earth". The first published use of extraterrestrial as a noun occurred in 1956, during the Golden Age of Science Fiction.[1]
Extraterrestrials are a common theme in modern science-fiction, but also appeared in much earlier works such as the second-century parody True History by Lucian of Samosata.[2]
This fiction is mostly for entertainment purposes, though it can also be used for satire, propaganda, education or political commentary.
In discussions about race, it is common to propose other colors of people to illustrate dynamics, educate about racism, or even to deny allegations of racism (eg., "I could care less if they were green!") It is unlikely that these proposed people are actually intended to be from outer space. They are likely just hypothetical or straw man human races.