Ptolemy XV Caesar, nicknamed Caesarion, was the last pharaoh of the Ptolemaic Kingdom of Egypt, reigning with his mother Cleopatra VII from 44 BC to 30 BC. He nominally reigned as sole pharaoh for a few days after his mother's death, although Alexandria had already fallen and Caesarion remained in hiding until his execution by Octavian, who would become the first Roman emperor as "Augustus".