In Norse mythology, the dragon associated with the Hero King Aurvandil is Nidhogg. Nidhogg is a serpent-like creature that gnaws at the roots of Yggdrasil, the World Tree, representing the connection between different realms of existence. This dragon embodies themes of disease and decay but also signifies the cycle of life and death. The relationship between Nidhogg and Aurvandil reflects the broader Norse beliefs about mythical creatures and their roles in the cosmic order, often viewed as both destructive and necessary for renewal.