The Macedonian king who conquered the largest contiguous empire in ancient history in just thirteen years -- from Greece to Egypt to Persia to the edge of India -- and whose campaigns spread Greek culture across the Near East in ways that shaped the ancient world for centuries.
He conquered an empire stretching from Greece to India before he was thirty-three, then died in Babylon with no plan for what came next. The empire dissolved immediately. What lasted was everything he spread along the way: Greek language, Greek city planning, Greek ideas about philosophy and science, now embedded across a world that had never been Greek before.