John Gielgud

Over the course of his career, he portrayed 9 Lords, 6 Kings, 4 Popes, 3 Prime Ministers, a couple of Saints, various military officers, Merlin the Magician, Cassius AND Julius Caesar, an orchestra conductor, a headmaster, a Marquis, and the houseboy of an idiot who's so pickled that he falls in love with Liza Minnelli. Guess that about covers it.