Ptolemy Caesar was one of the children of Mark Antony and Cleopatra in the Alternate Rome universe created by Iam. He ruled the Dominion with his siblings, but was minimally involved.

This was because he had ventured to the edge of the Dominion with his friend Agricola and saw how finite it was. He refused his brother's request to use 'Ultimus' (an atomic bomb), knowing how catastrophic it would be in such a confined area as the Dominion. Alexander therefore planned to assassinate Ptolemy and use Ultimus anyway, unaware of the consequences. The assassination failed, and on the day of the Games, Ptolemy goaded Alexander into the arena. They faced a pack of wolves, and the one who the wolves ignored would be ruler of the Dominion. Thanks to some pheromones from the TARDIS that Ptolemy applied to himself, the wolves attacked Alexander. After Iam duplicated the entire Earth and put it in a new solar system with the Alternate Rome, Ptolemy became the ruler without any challenge from his sister. (PROSE: State of Change)