A Prefect-King, or simply Prefect, was the ruler of Troyius, homeworld of the Troyian race. The position shared the roles of prefect and king. In 2268, this was Cosalthan II, who married Dohlman Elaan of Elas. The two then ruled both of their worlds jointly (ST reference: Star Trek Maps, FASA RPG module: The Orions: Book of Common Knowledge).