alien An extraterrestrial lifeform. A creature who is clearly not from planet Earth.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. 不要将这个标签用于与人类看上去无法区分的外星人角色。标记您所看到的，而不是您所知道的。