They worshipped one chief god, Odin, and other gods and goddesses who were his children.  Odin was often called All-father because he was the helper and friend of human beings, and appeared on earth in the form of an old man, “one-eyed and seeming ancient,” with cloud-blue hood and grey cloak.  He had courage, strength, and wondrous wisdom, for he knew all events that happened in the world, and he understood the speech of birds, and all kinds of charms and magic arts.  Men served him by brave fighting in a good cause, and when they perished in battle he received their souls in his dwelling of Valhalla in the city of Asgard, where they spent each day in warfare, and where at evening the dead were revived, the wounded healed, and all feasted together in Odin’s palace.  There they fed upon the flesh of the boar Saehrimner, which was renewed as fast as it was eaten.  Certain maidens called Valkyrie, or Choosers of the Slain, were Odin’s messengers whom he sent forth into the battles of the world to find the warriors whom he had appointed to die, and to bring them to Valhalla.

In the story of Sigurd Odin has a very important part to play, but for the understanding of the tale it is necessary to know something about another of the gods.  This is Loki, who, though sprung from the race of the giants, yet lived with the sons of Odin in Asgard, behaving sometimes as their trusty helper, but more often as their cunning enemy.  He caused much wretchedness, not only among the gods, but on earth also, for he delighted in the sight of misery.  His vices were all those most hateful to the Norse people, for he was before all things a liar, a deceiver, a faith-breaker, a skilful worker of mischief by guile instead of by fair fight.  There are many stories of his cunning thefts, of the miseries he wrought among his companions, and of his envy of the beloved god Balder, whom he slew by a trick.  His children were terrible monsters, as hated as himself.  Yet, strange to say, Loki was Odin’s companion in many of his adventures.

The gods inhabited Asgard, a city standing on a high mountain in the middle of the world.  Odin’s palace of Valhalla was there, and other palaces for his sons and daughters.  All round Asgard lay Midgard, or the ordinary world of men and women.  Its caves and waste places were inhabited by dwarfs, whom Odin had banished from the light of day for various ill deeds.  They were a spiteful and cunning race, jealous of mankind, and eager to recover their lost power.  Their strength lay in their wondrous skill in handicraft, for they could forge more deadly weapons, and fashion more lovely jewels than any made by the hands of men.  But, though possessed of wisdom, they had no spirit of kindness, no respect for right, and no dislike of wrong.

Around Midgard lay the sea, and beyond that Utgard, a hideous frozen country inhabited by giants, enemies of the gods.