Alien invasion or space invasion is a common feature in science fiction stories and film, in which extraterrestrial lifeforms invade the Earth to exterminate and supplant human life, enslave it, harvest people for food, steal the planet's resources, or destroy the planet altogether. It can be considered as a science-fiction subgenre of the invasion literature, expanded by H. G. Wells's seminal alien invasion novel The War of the Worlds, and is a type of "first contact" science fiction.
Aliens from Mars launch an invasion of Earth in H. G. Wells' The War of the Worlds, as illustrated by Henrique Alvim CorrĂȘa.
In Henry Slesar's 1958 story The Delegate from Venus, an alien robot cautions that Earth will be destroyed if its people do not learn to live in peace.
Extraterrestrials in fiction
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.
Extraterrestrials in fiction
Grey aliens were conceived as a result of the Barney and Betty Hill incident.