Technically a king or queen.
Probably also extends to an Emperor/Empress, especially if they are also King/Queen of a territory. Might extend as far as Prince/ess, where they have no superior above them. In Catholicism, would extend to the Pope (Vicar of Rome), as direct lineal representative of the Only True Monarch. --Simoncursitor 00:33, 7 Oct 2004 (EST)