Son of Ptolemy XII (r. 80–58 BC and 55–51 BC), he succeeded his father as pharaoh in the spring of 51 BC as co-ruler of the Ptolemaic Kingdom by his marriage to his older sister Cleopatra (r. 51–30 BC).
In October 50 BC, Ptolemy XIII was promoted to senior ruler along with her, although the eunuch Pothinus acted as regent for him.

In the spring of 48 BC, Ptolemy XIII and Pothinus attempted to depose Cleopatra due to her increasing status as queen.
Her face appeared on minted coins, for example, while Ptolemy XIII's name was omitted on official documents.
Ptolemy intended to become main ruler, with Pothinus acting as the power behind the throne.
Son of Ptolemy XII (r. 80–58 BC and 55–51 BC), he succeeded his father as pharaoh in the spring of 51 BC as co-ruler of the Ptolemaic Kingdom by his marriage to his older sister Cleopatra (r. 51–30 BC). In October 50 BC, Ptolemy XIII was promoted to senior ruler along with her, although the eunuch Pothinus acted as regent for him.
In the spring of 48 BC, Ptolemy XIII and Pothinus attempted to depose Cleopatra due to her increasing status as queen. Her face appeared on minted coins, for example, while Ptolemy XIII's name was omitted on official documents. Ptolemy intended to become main ruler, with Pothinus acting as the power behind the throne.
Ptolemy XIII Theos Philopator