Old Norse: Æsir
In Norse Mythology, the Aesir* were the principal race of gods (though the goddesses were sometimes called Asynjor). Headed by Odin, the Aesir were warlike, symbolizing power and wisdom, and they ruled the lives of mortal men. Their homes were two palaces in Asgard: Gladsheim, residence of the gods, and Vingolf, residence of the goddesses. Predictably, while the gods of the Aesir were immortal and very powerful, they were not infallible and they were subject to many human desires and weaknesses. In fact, without the apples provided by Idun, the deities aged rapidly.
Some of the primary deities of the Aesir were:
Odin, the All-Father
Balder, the god of beauty
Bragi, the god of eloquence
Forseti, the god of mediation
Freyr, god of fertility, originally of the Vanir
Heimdall, guardian of the Rainbow Bridge
Hod, the blind god
Loki, the trickster god of fire
Njord, the sea god, originally of the Vanir
Thor, the god of thunder
Tyr, the god of war
Vili, a brother to Odin**
Ve, a brother to Odin
Vidar, Odin’s son
Freya, the fertility goddess
Frigg, Odin’s wife
Sif, Thor’s wife
Idun, keeper of the apples of youth
The gods of the Aesir were of a younger race than the more gentle Vanir (who had mysterious roots in the time before creation). Odin was the oldest of the Aesir. His grandfather was Buri, who was formed when Audhuma’s licking melted a salt-block of Ginnagagap. Buri birthed a son, Bor, who was the father of Odin, Vili and Ve. The three gods, who disliked living under the rule of the giant Ymir, then created Asgard and Midgard, religious shrines*** and also gathered wealth for themselves. They determined the routes that the sun, moon and stars should follow. Odin, Vili and Ve also created the first humans: Ask and Embla. It is only after this point that other deities of the Aesir are mentioned.
After the creation of all things was finished, the first war erupted, which was between the Aesir and Vanir (headed by Heimdall). Some stories give the reason for the conflict as the Aesir’s denial of the Vanir’s godhood. Other sources blame the war on the murder of Gullveig, the oracle and sorcerer, who was visiting the Aesir. Rather than providing magic or insight, Gullveig over and over again told the Aesir of her love for gold (or,in some stories, corrupted them with drink). They listened to her until they could stand no more and then pushed her into a fire to kill her. But, though she was burned to ash three times, she survived each time (possibly being a variant of Freya). The attempted murder made the Vanir very angry and they made the first strike.
In the end, the Vanir and the Aesir declared a truce and the Vanir were assimilated into the Aesir. The two groups collectively were known as the Asa.
During Ragnarok, the gods of the Aesir will fight against the monsters and giants, with the exception of Loki, who becomes an ally of the frost giants. The treasures of the Aesir will be scattered throughout the worlds, and all the gods will be killed except for seven who go on to recreate the world:
Vidar, son of Odin
Vali, god of the battlefield
Honir (Hoenir), the long-legged god
Magni, son of Thor, god of might
Modi, son of Thor, god of wrath
Balder, god of beauty
Hod, the blind god
* The name Aesir might have been derived from the old-Teutonic word Ase, which was a common word for "god"
** It is interesting to note that the relatives of majors deities were recognized as gods but would usually not be worshipped. Presumably they existed merely to further the tales that illustrated the major deities' attributes.
*** It is not known to whom the shrines were built.