Nidhogg

Nidhogg (Nidhoggr, roughly "malice-striker") is named in both the Poetic Edda and the Prose Edda as a serpent or dragon at the bottom of the world-tree Yggdrasil, in or near the spring Hvergelmir, gnawing at one of its roots. The tree is thus under continual assault from below even as it upholds the cosmos, an image of decay working against order. In the Grimnismal a squirrel, Ratatoskr, runs up and down the trunk carrying insults between Nidhogg at the roots and an eagle at the crown.

In the Voluspa Nidhogg also chews the corpses of the dead in a grim hall on the shore of Nastrond ("corpse-strand"), where oath-breakers and murderers wade through venom; and in the poem's closing stanza the dragon appears once more, flying up with corpses in its wings, in a scene whose place in the world's renewal after Ragnarok is debated. Nidhogg is less a character with a story than a persistent image of gnawing dissolution at the foundations of things.

Nidhogg is best understood as one position in a system rather than as a character. Yggdrasil has a creature at every level: an eagle at the crown, four harts browsing the branches, goats and serpents, and the dragon below gnawing at the root. The squirrel Ratatoskr runs the length of the trunk carrying insults between the eagle and the dragon, which is the only piece of Norse cosmology that is straightforwardly funny.

What the arrangement describes is a tree under constant attack that goes on standing. Nothing in the sources suggests the gnawing will succeed. The tree suffers more than people know, one poem says, and that is the whole claim: the structure of the world is maintained against continuous damage rather than being permanent by nature.

The dragon's other post is Nastrond, the shore of corpses, where it feeds on the bodies of oath-breakers and murderers. The last stanza of the great prophetic poem has Nidhogg flying up over the plain with corpses in its wings, and editors have argued about that stanza for a long time, since a poem describing the world renewed after the end appears to close with the old horror still in the air. Some read it as the final note of an unresolved ending; others suspect it has been moved. The manuscript gives no help.