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).
- The sources disagree on the title of the leader of Troyius. The ST reference: Star Trek Maps says Elaan married "the Troyian Prefect", while the Decipher RPG module: Worlds has her marry "the Principus of Troyius". However, the FASA RPG module: The Federation says she married "the son of Troyius's current ruler", suggesting one of these alternative titles could be a lesser, prince-like position.