The Gray Fox is not just an assumed title, though, it is a curse from a Daedric Prince. Related: Elder Scrolls Online PS5 & Xbox Series X Upgrades Halve Load Times Wearing the cowl brings the notoriety of the famous thief, eliciting an immediate and hefty bounty if spotted by any guards. Through helping the current leader of the Thieves Guild in Elder Scrolls 4: Oblivion, the player becomes the highest ranking member of the Guild and dons the cowl, becoming the Gray Fox themselves.
The title is passed on to whomever becomes the Guild's leader. The Thieves Guild quest line in Oblivion is largely the story of the Gray Fox - or at least the current Gray Fox. The infamy of the Gray Fox is so great that many civilians cower in terror, and the local guards will attack the Gray Fox on sight. The Gray Fox has committed a notorious amount of crimes, and is only recognized by the trademark gray cowl that conceals their identity. That final moniker, the Gray Fox, is a venerated and legendary title reserved for the highest ranking member of the Cyrodiil branch of the Thieves Guild. In The Elder Scrolls IV: Oblivion, the player comes to bear many titles such as the Hero of Kvatch, Champion of Cyrodiil, Arch-Mage of the Mages Guild, Sheogorath, and the Gray Fox.