Alberich

Alberich was a legendary sorcerer who originated in the mythology or epic sagas of the Frankish Merovingian Dynasty of the 5th to 8th century AD, and whose name means king of the elves (elbe "elves" reix, rex "king"). He was also known as king of the dwarves.In the Nibelungenlied, an epic poem in Middle High German, he is a dwarf, who guards the treasure of the Nibelungen, but is overcome by Siegfried.In Wagner's opera cycle Der Ring des Nibelungen, Alberich is a dwarf and chief of the Nibelungen, and guardian of the "Rhinegold treasure". Wagner's Alberich is a composite character, mostly based on Alberich from the Nibelungenlied, but also on Andvari from Norse mythology.
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[Norse] A dwarven king, Alberich had his castle in a subterranean palace carved out of rock and ornated with gems and precious metal. He guarded the Nibelung hoard and was also a very powerful magician. He gave Siegfried the sword Balmung and a cloak which granted invisibility. Freya received the necklace Brisingamen along with Draupnir, Odin's ring, and the magical sword Tyrfing.