Helheim ("house of Hel") is one of the nine worlds of Norse mythology. It is ruled by Hel, the monstrous daughter of the trickster god Loki and his wife Angrboda.
This cold, dark and misty abode of the dead is located in the world of Niflheim, on the lowest level of the Norse universe. No one can ever leave this place, because of the impassable river Gjoll that flows from the spring Hvergelmir and encircles Helheim. Once they enter Helheim, not even the gods can leave. Those who die of old age or disease, and those not killed in battle, go to Helheim while those who die bravely on the battlefield go to Valhalla.
The entrance to Helheim is guarded by Garm, a monstrous hound, and Modgud. The giant Hraesvelg ("corpse eater") sits at the edge of the world, overlooking Helheim. In the form of an eagle with flapping wings he makes the wind blow.
It is no mistake that helheim sounds like Hell.