This books explores varying conceptions of the Nightmare hag, mara, in Scandinavian folk belief.What began as observations of some startling narratives preserved in folklore archives wheresex, violence and curses are recurring themes gradually led to questions as to how ruralpeople envisaged good and evil, illness and health, and cause and effect. Atcloser reading, narratives about the mara character involve existential themes, as well as comments on gender and social hierarchy. This monograph analyses how this female creaturewas conceived of in oral literature and everyday ritual practice in pre-industrial Scandinavia, andwhat role she played in a larger pattern of belief in witchcraft and magic.