Will-o’-the-Wisps are spirits in British/Celtic mythology that create little lantern-like lights off paths and roads to trick those that travel at night. If the travelers follow the lights they disappear into the bog, never to be seen again.
Source: Spirits, Fairies, Gnomes, and Goblins: An Encyclopedia of the Little People by Carol Rose
Image: Artist unknown. Source: Mudie, A Popular Guide to the Observation of Nature (1836, p.144)
This is a part of the World Mythology Challenge. Day 6 - Celtic Myth.