Ringwraiths

The Ringwraiths (also known as Nazgûl or Black Riders) were once great Men until they were given Rings of Power by Sauron. These gradually corrupted them until they became slaves of the Dark Lord's will. Clad in dark hooded cloaks and riding demonic steeds or flying "fell beasts," the Ringwraiths forever hunted for the One Ring to bring it back to their master.