Trolls, supernatural beings in Norse myth and North European folklore, are imaginary, not real. These frightening monsters have transformed from the non-Christian humanoid enemies of the Scandinavians into fantasy fiction's giant, indestructible brutes.
Like many legendary creatures from Northern Europe, trolls lived in mounds or caves. In Celtic lore, they are described as similar to ordinary people but uglier, notable for their fear of Christianity and prone to theft. Norse myth gives them multiple heads and arms. Trolls could use powerful magic, but were notably dim-witted. In later tales, trolls turned to stone when exposed to sunlight, and some tales claim standing stones, such as those found at Stonehenge, were originally trolls.