Nidhogg

Níðhöggr (Malice Striker) is a dragon or serpent who gnaws at a root of the world tree, Yggdrasil.

Etymology
In historical Viking society, níð was a term for a social stigma implying the loss of honor and the status of a villain. Thus, its name might refer to its role as a horrific monster in its action of chewing the corpses of the inhabitants of Náströnd: those guilty of murder, adultery, and oath-breaking, which Norse society considered among the worst possible.