Nidhøgg

Níðhöggr (Old Norse: Níðhöggr, "the one who strikes with malice") is a powerful serpent or dragon that gnaws ceaselessly on the roots of Yggdrasil in Niflheim, slowly undermining the very foundation of cosmic order. In Völuspá, Níðhöggr is described as one of the few survivors of Ragnarök — he flies over the new world with corpses in his wings. He also gnaws on the bodies of the damned at Náströnd, a shore in Hel.