The Devil (also known as Satan and by numerous nicknames) is a character in Christian and Islamic religious tradition. According to those traditions, he is the guardian of Hell, the place of torment where the souls of`the wicked go after they die. He is often considered to be the source of all evil and to be the entity which tempts people to do wicked or sinful things. Tradition says that he was originally an angel who rebelled against God and was sent to Hell as punishment. However, according to folklore and fiction, he frequently leaves Hell and visits Earth, either to try to gain more souls to join him in his place of punishment or simply to play pranks on people. He frequently appears in folklore, literature and popular culture.
According to Christian tradition, he was originally an angel named Lucifer who led an army of rebellious angels, seeking to overthrow and replace God. He was defeated and cast down to Hell as punishment. The other angels who joined Lucifer in his rebellion became demons and are his companions in Hell. According to Islamic tradition, the Devil was punished after he disobeyed God by refusing to bow down to the first man Adam.
Mainstream Judaism has never given much importance to the concepts of Hell or the Devil, although the Book of Job from the Hebrew Bible features a "satan" or "adversary" who disagrees with and challenges God. The Hebrew word for "adversary" was translated into Greek as "diabolos", which is the origin of the English word "Devil".
The Devil features prominently in European and American folklore. In many folktales, the Devil offers to make a deal with somebody, offering his help in return for the person's soul. However, the Devil is usually portrayed in those stories as losing out on the bargain and being easily outwitted. One example of such a story is the tale of Stingy Jack, the inventor of the jack-o-lantern. A variation on those folktales is the Faust legend, which says that people can sell their souls to the Devil in exchange for a limited period (usually twenty years) of wealth, power, and everything they could desire but have to go to Hell at the end of that period.
Well-known depictions of the Devil in literature are in Goethe's Faust, in which the character Mephistopheles says that he only represents a part of the Devil's power, John Milton's Paradise Lost, which describes Lucifer's rebellion against God and his banishment to Hell, and Dante's The Divine Comedy. According to Dante, the Devil can be found in the ninth and final circle of Hell, a realm not of fire but of ice. He is a huge monstrous figure, caked in ice up to his chest. He has enormous bat-like wings and three heads, one yellow, one red, and one black. In one of his heads he chews the body of Judas Iscariot, in the other two he chews those of Brutus and Cassius, the murderers of Julius Caesar.
The Devil is often depicted carrying a bident (a two-pronged fork) or a trident (a three-pronged fork). The standard modern image of the Devil is a horned, red-skinned man with a barbed tail, often with a neatly trimmed beard and mustache. He is often depicted with goat's legs, or at least a goat's cloven hooves instead of feet. However, he often appears in fiction as a shape-shifter who can take on any form he pleases.
Perceived connections with the Devil make many people, especially observant Christians and Muslims, feel uncomfortable about Halloween and are the reason why many people do not celebrate the holiday.