Auri-El

History
Auri-El is the Elven(or Aldmer) god, the same entity as Akatosh, the chief of the Nine Divines and of the Elven Pantheons. Auri-El is the soul of Anui-El who is the soul of Anu the Everything. 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 worlds 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 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.

Dawnguard
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 it's power from the sun, and is part of a prophecy foreshadowing the blocking-out of the sun. And you can find Auriel's Shield in 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.

The Chantry of Auri-El
The snow-elves built a 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.

Tyranny of the Sun prophecy
Knight-Paladin Gelebor's brother Arch-Curate Vrythur was turned into a Vampire. Because of this, Vrythur says that Auri-El turned his back on him, so he vowed revenge on the Deity. This resulted in Vrythur 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 couldn't actually confront the God.