Trolls were creatures in Norse* myth and legend who became part of the folklore of Scandinavia and northern Europe. Generally trolls were thought to be evil and dangerous, although sometimes they interacted peacefully with people. They were clever at building and making things of stone and metal and often lived in caves or among rocks.
Early stories described trolls as giants who lived in castles and roamed during the night. When exposed to sunlight, trolls turned to stone. The stone crags of a place called Trold-Tindterne (Troll Peaks) in central Norway are said to be two armies of trolls that once fought a great battle—until sunrise caught them and turned them to stone. Over time, trolls came to be portrayed about the size of humans or, in some cases, as small as dwarfs.
Many folktales tell of bargains between trolls and humans in which the humans must outwit the trolls or suffer sad fates. In one such story, a man named Esbern loved a girl whose father would not let his daughter marry until Esbern built a fine church. A troll agreed to build the church for Esbern on the condition that if Esbern could not discover the troll's name by the time the job was done, the troll would have Esbern's eyes and his soul. Try as he might, Esbern could not learn the troll's name. He was in despair until the girl he loved prayed for him. At that moment Esbern heard the troll's wife singing to her baby, and her song contained the name of her husband. After the people of northern Europe converted to Christianity, many of their stories featured prayer as a weapon against trolls.