The Yuuzhan Vong are a group of fictional characters from the Star Wars Expanded Universe. They rise as a threat to the New Republic in the New Jedi Order series of novels.
The Yuuzhan Vong and their Chazrach slaves are one of the few known alien species in the Star Wars universe to have originated outside the Star Wars galaxy. They are a race of religious zealots that genetically engineer and grow all of their technology organically and view mechanical technology as blasphemy. The Yuuzhan Vong endeavor to improve their physical capabilities through organ grafting. Notably, only one Yuuzhan Vong is able to touch the Force or seemingly be felt through it, something the Jedi find very mysterious, since all living things are supposed to have, in some way or another, a unique Force energy signature distinct from other species. Later, it is discovered they were stripped from the Force upon separation from their symbiosis with the sentient planet Yuuzhan'tar.
Read more about Yuuzhan Vong: Yuuzhan Vong Invasion