For use as the generic term 'alien' which generally refers to a life-form not of Earth, but it can also be used to describe anything, including objects, from another world or system. Use [aliens-1986] for the sequel to the 1979 film Alien; use [alien-franchise] for that entire franchise.

In science fiction, the term 'alien' generally refers to a life-form or being that is not human or of this planet. Typically, aliens come from a place other than the planet Earth, though occasionally they are from different dimensions. Aliens are a common recurring theme in science fiction.

Not to be confused with the movie franchise of the same name. Use for the sequel to the 1979 film Alien, for the sequel, and use for that entire franchise.