Zeus Ammon was a syncretic deity of early classical origins. Most of the facial features are human, but the ears and the coiling of the ram’s horns are bestial. The images of Zeus, the god of thunder and supreme deity of the Greeks, and Amun, the sun god of the ancient Egyptians, became closely connected in the minds of the Hellenic peoples over the course of long-standing contact between Greek and Egyptian cultures. Zeus Ammon’s sanctuary at the Oasis of Siwa in the Libyan desert was already famous when Alexander the Great made his pilgrimage there in 331 BC: a pivotal moment in the young king’s extraordinary life after the battle of Issus. Zeus Ammon became a tutelary deity of Alexander the Great, and posthumous images of Alexander depict him with the horns of Ammon.
In ancient Roman culture and mythology, Jupiter Ammon was also an important religious figure, though very different from the classical Greek cult figure of Zeus. Roman rulers used Jupiter Ammon as decoration on their armour on account of his protective powers, as well as for asserting the supremacy of the military.