Since ancient times, accounts of supernatural activity have mystified us. Ghost stories as we know them did not develop until the late nineteenth century, but the restless dead haunted the premodern imagination in many forms, as recorded in historical narratives, theological texts, and personal letters. The Penguin Book of the Undead teems with roving hordes of dead warriors, corpses trailed by packs of barking dogs, moaning phantoms haunting deserted ruins, evil spirits emerging from burning ca...