Alexander the Great (Born: July 20, 356 B.C. Died: June 10 or 11, 323 B.C.), also known as Alexander III, was an ancient Greek king (basileus) of Macedon (336–323 B.C.).  He was one of the most successful military commanders in history and was undefeated in battle.  By the time of his death he had conquered most of the world known to the ancient Greeks.