Pope John XXIII
This Sixties Pope is pretty much Chuck Berry to Pope Francis' Keith Richards. Like Francis, John XXIII was expected to be little more than a "caretaker" Pope. But in 1962, he convened the Second Vatican Council, an ecumenical throwdown that ended up dropkicking the Catholic Church out of the Dark Ages and into the modernity – it's the "Roll Over Beethoven" of Papal conclaves. Vatican II got rid of the super-boring Latin Mass, relaxed longstanding dogma and generally opened the door to a new kind of socially and politically liberal Catholicism.