The Vistani man Stanimir mentioned that his people live under the rule of the Dread Lord. This Lord allows only the Vistani to pass through his domain. He has a fearful reputation among his subordinates.
The Dread Lord's name must not be spoken, for it is an omen of bad luck.
The Dread Lord goed by the name of Strahd Von Zarovich, according to a Letter from Mansion we found in the Death House.