Who was Cleopatra replaced by on the throne?

For all practical purposes, Cleopatra's death ended the rule of the ancient kings and queens. Octavian/Rome took over Egypt. But the situation gets a little tacky as far as precision is concerned. Cleopatra had made her son, Ptolemy XV (Caesarion) her co-ruler according to law. This was okay during his childhood, but at the time of Cleo's death, Caesarion was a grown man and was actually the king of Egypt. He outlived her, so for a brief time he was the Egyptian ruler. (Just a brief note: Caesarion was 17 years old at the time, but in the ancient world he would have been considered an adult).