Ammon, the Greek and Roman name for the ancient Egyptian god Amen, ä'měn. The name is also written Amon and Amun. Ammon originally was a local deity in Thebes. When the local princes of Thebes became masters of all Egypt about 2000 B.C., Ammon became a national god worshipped throughout Egypt. Gradually his name was joined with that of the Egyptian sun-god Re as Amen-Re. He also became the god of oracles. Ammon sometimes is pictured as a ram or as a man with a ram's head.