“Will O’ The Wisp” from Wikipedia – recently popularized by Pixar’s Brave
A will-o’-the-wisp /ˌwɪl ə ðə ˈwɪsp/ or ignis fatuus (pron.: /ˌɪɡnɨs ˈfætʃuːəs/; Medieval Latin: “foolish fire”) is a ghostly light seen by travellers at night, especially over bogs, swamps or marshes. It resembles a flickering lamp and is said to recede if approached, drawing travellers from the safe paths. Afolk belief well attested in English folklore and in much of European folklore, the phenomenon is known by a variety of names, including jack-o’-lantern, hinkypunk, and hobby lantern in English.