Monstrous ex-peculiars who hunger for the souls of their former brethren. Corpselike and withered except for their muscular jaws, within which they harbor powerful, tentacle-like tongues. Especially dangerous because they're invisible to all but a few peculiars, of whom Jacob Portman is the only one known alive. (His late grandfather was another.) Until a recent innovation enhanced their abilities, hollows could not enter loops, which is why loops have been the preferred home of peculiars.