A dragon is always a dragon and a vampire is always a vampire, but the troll went from a shape-shifting, sun-swallowing demon of the Norse wilderness to a plastic doll with a gem in its belly. This deep dive unpacks that bizarre evolution and starts with a surprising fact: the Vikings themselves did not know what a troll was. The word traced back to a Proto-Germanic root meaning to tread or step on, and in early Old Norse it was a blanket term for anything dangerous or unnatural.

We follow the troll from the ninth-century encounter in the Prose Edda, where a troll woman confronts the poet Bragi with cosmic poetry and he answers with verse, to the Christianization of Scandinavia that shrank trolls into human-looking outsiders who kidnap people and overrun farms. We examine church bells, lightning, and sunlight as the folk explanations for their disappearance, the burial-mound folk of later centuries, and the provocative theory that troll legends preserve a memory of encounters with Neanderthals.

• The scholarly debate between Lotte Motz’s neat categories and Armann Jakobsson’s catch-all reading
• How glacial boulders became rocks thrown by trolls at new churches
• Why the fear of lightning is a lingering echo of Thor
• John Arnott MacCulloch’s theory connecting mound-dwelling trolls to spirits of the dead
• Why a Norwegian research station in Antarctica is named Troll