From Unofficial Handbook of the Virtue Universe
The Norse people worshipped gods from three different tribes.
Aesir: A warlike tribe of gods, who achieved their position through conquest, and who are strongly associated with war and violence.
Vanir: A tribe of nature and fertility gods, who were bound to the Aesir after a great war.
Jotun: A tribe of elemental nature spirits, who were seen as giants, competitors with the Aesir. At the Ragnarok, the fire Jotun will be a major portion of the forces arrayed against the Aesir and Vanir.