Garm is a monstrous hound that guards the entrance to Helheim, the realm of the dead. He has four eyes, and snarling jaws dripping with blood. He lives in the cave Gnipa. On the day of Ragnarok, Garm will join the giants in their fight against the gods. Garm will be killed by the god of war Tyr, but Tyr will also die from the wounds inflicted by the hound.

Garm is often equated with the wolf Fenrir. He is also known as the Hound of the Underworld.