Vahlok the Jailer

Vahlok the Jailer was one of the most powerful Dragon Priests during high influence of the Dragon Cult on Solstheim. His name translates to "Guardian", which basically tells of what he was.

History
At some point in time, his contemporary, Miraak, was seduced by promisings of great power by Hermaeus Mora, Daedric Prince of Fate and Knowledge. Miraak learned great power from him and decided to turn against his dragon overlords. He tried to do so in secret, but Vahlok found out and confronted him. The dragons tasked Vahlok with defeating Miraak and, after lengthy battle that supposedly separated Solstheim from mainland of Skyrim, he did.

For his victory, he gained much glory and the dragons appointed him as the ruler of the island. But before doing so, they made him compel to swear an oath of vigilance, to look for Miraak's return.

Legacy
Legends speak of him being the symbol of loyalty and nobility in his battle against Miraak and goes as far as being inspiration in both man and dragon. His reign over Solstheim was remembered as being prosperous and he was remembered as being wise and just leader to the people of the ancient Skaal.