Alien

An alien is a general term for any entity which is not from your native planet. In most occurrences, this means entities which are not native to Earth, from the viewpoint of the humans. This can include both sentient and non sentient creatures, as well as most extraterrestrial robots.


 * The Doctor referred to the Silurians as an alien race in Doctor Who and the Silurians. This might imply that they are actually not native to Earth, or the Third Doctor was simply uninformed.