Will-o’-wisp is the most common name for the ghost lights found in English folklore. Described as floating balls of light, they are elemental spirits who will try to lead travellers astray.
Usually seen at night, will-o’-wisps will try to tempt a traveller into following them. Some say that the will-o’-wisp will be satisfied by causing their victim to become lost, while others believe them to be more malevolent, looking to lead people into bogs and other bodies of water, where they will drown.
There are a few tales where the will-o’-wisp is painted in a positive light, leading lost travellers to safety, or even treasure.