In the Norse pantheon, Asgard was the home of the gods, and it was the place where one could find Odin, the supreme deity of them all. Connected to his Germanic ancestor Woden or Wodan, Odin was the god of kings and the mentor of young heroes, to whom he often gave magical gifts.
In addition to being a king himself, Odin was a shapeshifter, and frequently roamed the world in disguise. One of his favorite manifestations was that of a one-eyed old man; in the Norse Eddas, the one-eyed man appears regularly as a bringer of wisdom and knowledge to heroes. He pops up in everything from the saga of the Volsungs to Neil Gaiman's American Gods. He was typically accompanied by a pack of wolves and ravens, and rode on a magic horse named Sleipnir. Odin is associated with the concept of the wild hunt, and leads a noisy hoarde of fallen warriors across the sky.
Odin was said to summon dead heroes and kings to Valhalla, which they entered accompanied by the host of Valkyries. Once in Valhalla, the fallen engaged in feasting and combat, always ready to defend Asgard from its enemies. Odin's warrior followers, the Berserkers, wore the pelts of a wolf or bear in battle, and worked themselves up into an ecstatic frenzy that made them oblivious to the pain of their wounds.
As a young man Odin hung on the world tree, Yggdrasil, for nine days while pierced by his own javelin, in order to obtain the wisdom of the nine worlds. This enabled him to learn the magic of the runes. Nine is a significant number in the Norse sagas, and appears frequently.
Odin continues to maintain a strong following, particularly amongst members of the Asatru community.