Nidhogg is a dragon or serpent in Norse mythology that is known for gnawing at the roots of Yggdrasil, the World Tree. This creature symbolizes destruction and decay, as it feeds on the dead and represents the darker aspects of existence in the Norse cosmos. Nidhogg’s actions highlight themes of death, rebirth, and the cyclical nature of life, connecting to various mythological narratives about the afterlife and the fate of souls.