In folklore, a spirit which appears in the form of a light and leads belated travelers astray, often into bogs and marshes. Will-o'-the-wisp is now the most common form. Other names or variants include Will with (a) wisp, Willy-ba-wisp, Billy of the wisp, Jack-o'-lantern, Jack of the wad (Jack o' t' wad), Joan in the wad, Jenny with the lantern, Jemmy Burty, Peggy-lantern, Gill Burnt-tail (Gillian a Burnt-tail), Kit with the candlestick, Kitty with the wisp, etc.

At Gough, another name was Sylham lamp: In the low grounds at Sylham, just by Wingfield in Suffolk, are the Ignes fatui, commonly called Sylham lamps, the terror and destruction of travellers and even the inhabitants, who are frequently misled by them.

In Warwickshire, the term mab-led (pronounced mob-led) signified being led astray by a will-o'-the-wisp. This was the Mab of fairy-lore.

"Ah, homely swains! your homeward steps ne'er lose;
Let not dank Will mislead you to the heath;
Dancing in murky night o'er fen and lake;
He glows to draw you downward to your death,
In his bewitch'd, low, marshy willow brake!"
William Collins

In Germany it is called irrlicht, in Dutch dwaallicht, and in French feu follet. See also ignis fatuus.

The natural explanation is that these are phosphorescent lights caused by the spontaneous combustions of gasses given off by rotting organic matter.



  • Omens and Superstitions: Curious facts and illustrative sketches. (1868). Edinburgh: William P. Nimmo, p. 11.
  • Bonnerjea, Biren. (1920). A Dictionary of Superstitions and Mythology. Thomson Gale.
  • Hazlitt, W. Carew. (1905). Faith and Folklore. 2 vols. London: Reeves and Turner, p. 2:535 ff.
  • Scott, C.P.G. (1895). "The Devil and His Imps: An Etymological Inquisition." In Transactions of the American Philological Association. Vol. 26. Boston: Ginn & Co.