His father was a king and he was a prince but he walked away from that position as a young man. He assumed no secular leadership role (king or emperor) in his later life.
Yes, Alexander the Great did become emperor. He was already the son of a king and when his father died, he inherited his power and a powerful military, which he used to create his vast empire.
JULIUS CAESAR DID MOT BECOME KING OR RULER OF THE ROME BECAUSE HE WAS NOT CONFIDENTLY IN RULLING ROME VERY MUCH.YET HE LOVED ROME VERY MUCH BUT HE DID NOT WANT TO BE SUCCESSOR OF THE PREVIOUS KING. PS.He didn't become Emperor because Emperors were hated and feared at that time.
He did not become king of the Greeks, he was Hegemon (Leader). He could claim kingship of the Persian Empire when Persian emperor Darius was killed in 331 BCE.