Andvari

In Norse mythology, Andvari was a dwarf who lived underneath a waterfall and had the power to change himself into a fish at will. He had a magical ring named Andvarinaut, which helped him become wealthy. Using a net provided by Ran, Loki caught him as a trout and forced him to give up his gold and Andvarinaut. Andvari cursed Andvarinaut to destroy whoever possessed it. After the deaths of Brynhild (Brünnehilde) and Sigurd (Siegfried), Gunnar (Gunther) left Andvari's gold in a cave. Years later, Andvari discovered the cave and his lost gold, although his ring was lost forever. In Richard Wagner's cycle of music dramas, Der Ring des Nibelungen, the character Alberich is based in some part on Andvari, but more on the Frankish sorcerer Alberich.