We all know about vampires and werewolves, or at least we think we do. The legends and myths that inspired these monsters are sometimes surprisingly different, but no less chilling. In this series of posts, Monster Monday, we’ll investigate the monsters that have informed our modern notions, as well as some lesser known monsters. Today, we talk about the Will-o’-the-wisp.

The will-o’-the-wisp, often called jack-o’-lantern or ignis fatuus (Latin for “foolish fire”) is a ghost light in European folklore that leads travelers astray at night, sometimes to their deaths. It moves on its own, and will retreat when approached, leading the traveler further and further from the safe path. Sometimes, it goes out, leaving the traveler lost in the darkness. It is often seen near marshes, bogs, swamps, and graveyards. When seen near graveyards, it is sometimes called a “ghost candle.”

In many places, the will-o’-the-wisp is said to be the soul of an unbaptized person, trapped between heaven and hell. In the British Isles, the will-o’-the-wisp is often associated with the faeries. In some parts of Continental Europe, the ghostly light is said to mark the location of buried treasure. This belief is repeated in the first chapter of Dracula by Bram Stoker.

Though many have attempted, there is still no widely accepted scientific explanation for the will-o’-the-wisp. A popular theory is the ignition of marsh gas, but it does not explain the behavior of the light. Another is that the will-o’-the-wisp is somehow related to the atmospheric phenomenon ball lightning. Still another hypothesis is that it is the result of the oxidation of certain phosphorus compounds.

The names will-o’-the-wisp and jack-o’-lantern come from related legends of a man named Will or Jack who is so evil he is denied entrance to either heaven or hell and is forced to wander the earth forever. As an act of mercy, he is given a single piece of coal to warm himself, and depending on the version, he uses it to light a torch (also called a wisp), or he places the coal in a lantern.