Fenrir (mythology)

Fenrir is a monster in Norse mythology and one of several monstrous offspring born to the traitorous god known as Loki - Fenrir was born an abnormally large and powerful wolf with great intelligence but an evil temperment and became a formidable enemy of the gods until they arranged for mystical chains to be forged to contain the monstrous beast until the day of Ragnarok - upon which Fenrir would be released alongside all other evils in order to engage in Ragnarok.