Hostile Aliens

Hostile Aliens are those known to violently attack others without provocation, whether or not they see their own behavior as perfectly reasonable and/or justifiable in their own alien sense of morality. They often seek the annihilation, enslavement or subjugation of entire races.

They're different from aggressive aliens: in which individuals regularly act with hostility towards their own kind rather than, or in addition to, others. As such, all aggressive aliens are hostile, but not all hostile aliens are aggressive. Predatory aliens are different too, in that they attack not out of sheer violence, but to obtain something from their victims, be it resources, power or something else.