The Ruler of the Universe, also known as the King of the Universe (AUDIO: The Emporium at the End) or the President of the Universe, (AUDIO: The City and the Clock, etc.) was the leader of the Unbound Universe.
With everybody in line dead following the Great War, the Unbound Doctor became Ruler of the Universe (AUDIO: The Emporium at the End) and enjoyed varying degrees of popularity. (AUDIO: The City and the Clock, Asking for a Friend, The True Saviour of the Universe) The Parliament of the Universe eventually stripped him of the position and gave it to the Unbound Master. (AUDIO: The True Saviour of the Universe)