Death, The Defeater of Empires, the swallower of Oceans, the Thief of Years, the Ultimate Reality, the Harvester of Mankind, the Assassin against Whom No Lock Will Hold, the only friend of the poor and the best doctor for the mortally wounded. An anthropomorphic personification. Almost the oldest creature in the universe (obviously something had to die first).
He is a seven-foot tall skeleton of polished bone, in whose eye sockets there are tiny points of light (usually blue). He normally wears a robe apparently woven of absolute darkness. He is seen only by cats, professional practitioners of magic, and those who are about to die or are already dead.
Despite rumour, he is not cruel. He is just terribly, terribly good at his job.