Garm
Hell-hound. Garm was the giant hound that guarded the gate in Hel (the world of the dead). (Garm was very much like the three-headed Ceberus, who also guarded the Underworld in Greek myths.)
Garm was bound by rope in Gnipa-cave, or Gnipahellir.
Although Tyr killed Garm at Ragnarök (Ragnarok), the war-god died from his severe wounds that the hound inflicted on him.
By Jimmy Joe