emperor

Caesar, czar (also tsar), czarina (also tsarina), emir (or amir), empress, kaiser, khan, khedive, king, lady, lord, mikado, mogul, prince, princess, queen, satrap, shah, sultan, sultana, suzerain

autocrat, monarch, potentate, ruler, sovereign (also sovran)

coruler

authoritarian, Big Brother, despot, dictator, führer (or fuehrer), monocrat, overlord, paramount, tyrant