In the fictional Star Trek universe, Pah Wraiths are evil Bajoran Prophets, non-corporeal life-forms, who were expelled from the Bajoran wormhole and reside in caves on the planet Bajor. They long for revenge against the prophets who cast them out, even going so far as to possess the bodies of corporeal beings to further their goals. Keiko O'Brien, wife of Deep Space Nine Chief of Operations Miles O'Brien, was used in a nearly successful attempt to kill the prophets. (Episode: "The Assignment")