The Einherjar (Einheri in the singular in Old Norse; "those who form an army" or "those who fight alone") are, in Norse mythology, exceptional warriors who died bravely in battle.
The Valkyries chose the Einherjar and carried them away. Some warriors who wished to survive these battles did not look up to avoid attracting the attention of the Valkyries, who could have killed them in order to take them away.
They escaped, to their great satisfaction, the "death of straw", that is to say the natural death in their bed, which destined these spirits to take the path of Helheim where Hel, goddess of death whose face is half immersed in the shadow of darkness and the other half in the light of life, led them on a ship to follow the current of one of the twelve rivers, the Elivágar, one of which opened in the Gardens of Asgard.
A completely different destiny awaited these Einherjar. The warrior goddess Freya, riding her horse and accompanied by the Valkyries, took these glorious fighters to Asgard. Half of these heroes went to Valhalla, to Odin's palace, the other half to Folkvangr, Freya's palace.
The warriors devoted to Odin are those among them who dedicate their existence to war and battle, "the offensive".
The warriors devoted to Freya are those among them who fight to protect their families, their clans and their property, "the defensive".
The historian Else Roesdahl has indeed noticed that, in the graves containing weapons, the warriors had shields that she calls the defensive, the others had only their weapons of attack that she calls the offensive.
Odin's warriors are awakened each day by the rooster Gullinkambi, to go to the vast field of Idavoll located in the center of Asgard to fight each other in joyous and deadly battles.
At dusk, the dead come to life, the wounded heal, and all gather at Odin's banquet, where they feast with the Valkyries.
They drink mead from the udders of the goat Heidrun, perched on the roof of Valhalla; Andhrímnir, the cook of the gods, has prepared a meal in the cauldron Eldhrímnir with the flesh of the boar Sæhrímnir.
The animals of the gods all have a name, which shows the importance they give to their companions, they are so concerned about their well-being that they even give them life when they eat them.
Also the generous boar Sæhrímnir comes back to life every morning to be consumed every evening.
The Vikings believed that if they died in battle, they would be taken to Valhalla by the Valkyries, to join the army of Einherjar and thus help the gods in their fight against the forces of chaos in the final battle of Ragnarök.
The Einherjar appear in the video game Age of Mythology, where they are the mythical units of the god Heimdall.