Marx would be little remembered without the opportunist Lenin.
Washington is often taken for granted but Lord was he pivotal.
For various reasons I would add Augustine and then Erasmus/Luther combined.
Pythagoras, Archimedes, Aristotle, Copernicus, Galileo, Kepler, Leeuwenhoek, Newton, Boyle, Lavoisier, Maxwell, Kelvin, Einstein, Szilard, Teller, and Oppenheimer.