Miraak

Miraak was one of the most powerful Dragon Priests that reigned during high influence of the Dragon Cult in Solstheim. Apart him being Dragon Priest, he was also a Dovahkiin.

History
During dragons rule over mortals in Merethic Era, Miraak served as Dragon Priest on island of Solshteim. At some point in time, he came into possession of a Black Book, which in turn led him under the servitude of Daedric prince of Knowledge and Fate, Hermaus Mora. Learning great power from him, he turned against his dragon overlords. Even the Ancient Nord Heroes, Hakon One-Eye, Gormlaith Golden-Hilt and Felldir the Old, pleaded him to use his power as Dragonborn to help them defeat Alduin, but he refused and attempted his own rebellion against them.

His rebellion was unsuccessful, the dragons razed his Temple and Miraak was defeated by another Dragon Priest, Vahlok, which was made his jailor. Other sources claim, Vahlok was about to kill Miraak, but then Hermaus Mora saved him by transporting him to his realm of Oblivion, Apocrypha. Vahlok was made the ruler of the island, but not before he was compelled to swear the oath of vigilance to look for Miraak's return.

Miraak stayed in Apocrypha up until 4E 201, when he tried to rebel against Hermaus Mora himself.