Nidhogg or Níðhöggr, is the dragon who gnaws at the roots of Yggdrasil, the world tree. Nidhogg’s appearance resembles that of a sinister black scaled slender dragon with four prominent horns outstretched from his face, and several spikes running along his back. He has six large leathery black wings sprouting from his back and several curved horns spiraling under his neck. His snout has a prominent underbite and chin spike. He has red ominous eyes.