Appearing as strange hybrids of other animals, the extradimensional Yanoth-Yith have heads which resemble that of a warthog, leonine bodies, alligator-like tails, and the great, leathery wings of a fruit bat. Their claws are razor sharp and their eyes are pinpoints of black flame. The Winged Horrors are a parasitic breed who are capable of siphoning the life energy from another creature and, if bound using the proper rituals, passing this energy on to another. In addition, a summoned Yanoth-Yith is able to inhabit the body of a sacrifice, an in this fashion pass itself off as human.
One-hundred and forty years ago a sorcerer by the name of Marcus Withers sacrificed his daughter through dark magic and called up a Yanoth-Yith in order to prolong his own life. However, when reinforcing the binding rites, Withers made a mistake and the entity was able to effect an escape, and later return and kill the old magician.
Over the next few weeks, it stalked the town of Burrillville, preying on its citizens for sustenance. Eventually locating pages from the cursed book the Necronomicon, the creature then attempted to open a gateway to its own dimension in order to call forth more of its kind. As luck would have it, a group of friends had also turned up pages from the Necronomicon, and were able to recite the proper incantations in time to close the door and thwart the Yanoth-Yith's plans.
- The Yanoth-Yith made their only appearance in the short story The Blackness over Burrillville (1991), by Arthur Levesque.