The Gray Fox

The Gray Fox is more of a rumor than anything. He is thought to have existed for over 300 years and that he is able to vanish into thin air. The Gray Fox is not just one man, however. Anyone who wears the Gray Cowl of Nocturnal is considered to be the Gray Fox. The cowl itself was stolen from the Shrine of Nocturnal over three centuries ago by the first Gray Fox, Emer Dareloth. The Cowl has been passed down to subsequent Guild Masters when their time comes, including the Count of Anvil Corvus Umbranox and the player if they complete the Thieves Guild questline. 
 
The Thieves Guild questline ends with a notably long quest where players must steal an Elder Scroll. Once the quest is completed, the Gray Fox gives the player one final task. He wants he/she to bring a ring to the Countess of Anvil. When given the ring, the Countess recognizes it as the ring her husband had who disappeared 10 years earlier. At that moment, a stranger approaches the throne and explains that Emer Dareloth stole the Cowl from the Shrine of Nocturnal and that he is not only the Countess' husband but also the Gray Fox. He had used the power of the Elder Scrolls to break the curse, allowing him to remove the Cowl and be a free man. He gives the player the Cowl and promotes him to the position of Gray Fox.