Nidhogg ("Tearer of Corpses") is a dragon that lives at the roots of the tree Yggdrasil in Niflheim. He perpetually gnaws at the roots of this tree, threatening to destroy it. He trades insults with the falcon Vedfolnor who sits on the brow of an eagle located on the topmost bough of the world tree, Yggdrasil. The insults are carried back and forth by the squirrel Ratatosk.

Nodhogg lies on Nastrond in Niflheim, were it also eats corpses to sustain itself. Nidhogg is not the only serpent whose task it is to destroy the World Tree. Other serpents include Graback, Grafvolluth, Goin and Moin.

Also known as: Nidhoggr