Einherjar

In Norse mythology, Einherjar referred to the spirits of warriors who had died bravely in battle. Half of them were escorted from the battlefield after dying by the Valkyries (these are what is referred to as "einherjar"); the other half went to Sessrumnir, Freya's hall. The einherger live on in Valhalla, a sort of Heaven. Every day they are awoke by Gullinkambi, a rooster, to train all day until they are all cut to pieces. At night, they eat from the god Odin's body and are reborn. During Ragnarok, Odin will call up the Einherjar to fight the frost giants.

Alternative: Einheriar