Auri-El is the Elven variant of Akatosh, the chief god of the Nine Divines. Auri-El is the soul of Anui-El, who in turn is the soul of Anu, the Everything. He is often seen as chief of the Aldmeri Pantheon, by his followers.
Most Altmer and Bosmer claim direct descendance from Auri-El. In his only known moment of weakness, he agreed to take his part in the creation of the mortal plane. That act forever sundered the Elves from the spirit's world of eternity. To make up for it, Auri-El led the original Aldmer against the armies of Lorkhan in the Mythic Era. Together Auri-El, Trinimac, and the Aldmer vanquished Lorkhan and established the first kingdoms of the Aldmer, Aldmeris and Old Ehlnofey. He then ascended to Heaven in full observance of his followers so that they might learn the steps needed to escape the mortal plane.
The Chantry of Auri-ElEdit
The Snow Elves constructed a large temple called "The Chantry of Auri-El", which encompasses many caves and the Forgotten Vale. The Chantry was reportedly the most significant place of Snow Elf worship for any Elven god, and was the main place of worship for Auri-El. The Chantry has several Wayshrines, that pilgrims are required to visit in order to gain an audience with the Arch-Curate, in the Inner Sanctum of the Chantry. The Arch-Curate is presumably the religious leader responsible for Snow Elf worship of Auri-El. Because of the isolated nature of the location, it is understood that it may be the last location of pure Snow Elves who have not been tainted by the Falmer, however it is possible that there are isolated groups elsewhere in Tamriel.
Tyranny of the Sun ProphecyEdit
Knight-Paladin Gelebor's brother Arch-Curate Vyrthur was turned into a Vampire. Because Auri-El did not cure him as he had requested, Vyrthur believed that Auri-El had turned his back on him, so he vowed revenge on the god. This resulted in Vyrthur writing the prophecy that the Sun would be blocked out by a vampire. He did this to limit Auri-El's influence on Mundus, because he knew that he could not actually confront the god.
In The Elder Scrolls V: Dawnguard, part of the main questline requires the Dragonborn to find and secure Auriel's Bow. Auriel's Bow is a weapon that supposedly draws its power from the sun, and is part of a prophecy foreshadowing the blocking-out of the sun. You can also find Auriel's Shield in the Forgotten Vale. In Darkfall Cave, the Dragonborn encounters one of the two remaining Snow-Elves (also known as Ancient Falmer), named Knight-Paladin Gelebor. Gelebor gives a brief history of his race, and their beliefs. He explains that Auri-El is known by many names, and that he was the main god for the Snow-Elf race.