Alien

An alien is a general term for any entity which is not from the 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 Third Doctor once referred to the Silurians as an alien race. This might imply that they are actually not native to Earth or more likely that he was simply uninformed.