Ignus Fatuus

Entry in A Dictionary of Ghost Lore
Ignus Fatuus, or "foolish fire" is the general term given to the ghostly phenomena, variously known as jack-o'-lantern, will-o'-the-wisp, corpse candle, etc. These strange dancing lights, which are said to be oments of death, have been widely reported throughout Europe and anyone foolish enough to follow one is said invariably to be lead to their death in treacherous marshland. Although they are now generally believed to be caused by ignighting marsh gases, legend has it that the light belongs to a ghost named Will the Smith, a man so wicked he was barred from both heaven and hell and condemned to wander lonely paces with only a flickery light t show him the way. The traditions of ignis fatuus are discussed in some detail in Katherine Briggs's A Dictionary of Fairies (1976).