An extraterrestrial lifeform. A creature who is clearly not from planet Earth.
Aliens in science fiction are often depicted as basically humanoid with a few non-human characteristics, such as colored skin or unusual appendages. Unintelligent aliens are often depicted as monsters or creatures.
Don't use this tag for alien characters who look indistinguishable from humans. Tag what you see, not what you know.
For the aliens from the Alien series, see the xenomorph tag.
