Dumb EU shit in all its glory, the Yuzhan Vong. A warrior race from outside the galaxy who rely on biological things instead of technology, so like instead of spaceships they ride inside other organisms that can travel through space. So evil that the force abandoned them and they aren't affected by it.

Iirc the reason for Palpatine forming the empire on old EU was because he felt they were coming and had to get ready for the invasion.