Andvari

Andvari is a dwarf who lives as a pike in a waterfall, hoarding a treasure of gold. When Loki, needing a ransom for the otter Otr he killed, captures him in Ran's net, the dwarf surrenders his entire hoard. He tries to keep one ring, Andvaranaut, but Loki strips it from him too. Enraged, Andvari curses the gold and the ring to destroy whoever owns them. The curse runs through the whole Volsung saga: it kills the dragon Fafnir, dooms Sigurd, and brings down the Gjukungs. His brief, bitter appearance sets the bloodiest tragedy in Norse legend in motion.