Fenris

Fenris is the son of Loki and the giantess Angrboda, and the brother of Hel and the Midgard serpent. Described as a large wolf, he is one of the forces which will bring about Ragnarok, the last battle that will destroy earth. Fenris was bound though Tyr's effort, though Tyr lost his hand in the process.

The Fenris Wolf, also known as Fenrir, was a very big supernaturaal wolf. The Aesir felt threatened by him, but could not kill him, due to his divine parentage. They tried first to bind him with two chains of increasing strength, known as Leading and Dromi. Fenris broke both of these chains. The Aesir then turned to the dwarves to fashion a fetter made from six secret things: The sound of a cat moving, the breath of a fish, the beard of a woman, the sinews of a bear, the roots of a mountain, and the spittle of a bird. It was known as Gleipnir. Fenris did not trust this sleight bond, and so he insisted that one of the Aesir place their hand in his mouth when he was bound. Only Tyr was brave enough to do so. When Fenris found that he could not break Gleipnir, he bit off Tyr's hand. Fenris is fated to remain bound until Ragnarok, the final battle between the Aesir and the forces of destruction, led by Loki. Upon that day all bonds are destined to fail, and Fenris will be released. He and Tyr are fated to kill one another in the final battle.