A skeleton is a type of physically manifested undead often found in fantasy, gothic and horror fiction, and mythical art. Most are human skeletons, but they can also be from any creature or race found on Earth or in the fantasy world. Animated human skeletons have been used as a personification of death in Western culture since the Middle Ages, a personification perhaps influenced by the valley of the dry bones in the Book of Ezekiel. The Grim Reaper is often depicted as a hooded skeleton holding a scythe (and occasionally an hourglass), which has been attributed to Hans Holbein the Younger (1538). Death as one of the biblical horsemen of the Apocalypse has been depicted as a skeleton riding a horse.