Will o' the wisp, also called wisp or will-o-wisp, are one of the many strange monsters found in the Dank Wilderness. Little is known about them except that they appear as points of light, dancing at night in swamps and boggy areas. Geralt met some in the Dank Wilderness.
Some appear in the Blood and Wine expansion as part of the Land of a Thousand Fables. While Syanna tells Geralt to be careful and not to trust them, fortunately the two in the fairytale land are benevolent and lead to loot.