In Norse mythology, Odin commands the fallen warriors of Valhalla at Ragnarok. These warriors, called the Einherjar, are gathered after death and prepare for the final battle.
Valhalla is Odin’s hall in Asgard. According to the mythic tradition, the Einherjar fight one another during the day and feast at night, training for the conflict that awaits them.
Odin’s role is not simply that of a ruler collecting heroes. He is also a god of wisdom, war, poetry, and death, so his connection with battle casualties and prophetic knowledge is central to the Ragnarok story.
The Valkyries choose or guide many of the slain to Odin’s hall. Other dead are associated with Freyja’s field Fólkvangr, so not every fallen warrior necessarily goes to Valhalla.