Garm

Garm is the great blood-stained hound that guards the gates of Hel, chained before the cave Gnipahellir at the edge of the underworld. The Voluspa names his howling as a sign that Ragnarok has come, a refrain that tolls between its verses: Garm bays loudly, the fetter will break, the wolf run free. When the end arrives he slips his bonds and meets Tyr, the one-handed god of war and law; the two slay each other in the last battle. Some take him for Fenrir under another name, others as the Norse kin of Cerberus, the dog that keeps the dead from crossing back.