Alberich

Alberich is the main antagonist in "The Invisible Library" series by Genevive Cogman.

Alberich is a character in Mercedes Lackey's Valdemar series of books - He is a master swordsman and a Herald.

Also an important character in Richard Wagner's Der Ring des Nibelungen. He's the dwarf who curses love and thus he can steal the Rhinegold, which he forges the Ring from, and becomes a king of Nibelungs. Later he loses the Ring due to Loge's and Wotan's treachery. He curses the Ring and all the later bearers.