younger son and co-ruler with Ptolemy VI Philometor, king of Egypt, whom he succeeded in 145 BC. Still a minor, he was the ward of his mother, who also served as his co-ruler. He was soon displaced by his uncle, Ptolemy VIII, who executed him the following year.

Classical and even contemporary Egyptian sources are confused concerning the placement of Neos Philopator in the royal sequence because at least one other son of Philometor, also named Ptolemy, served as co-ruler earlier in the reign. Modern scholars have gathered evidence to show that Neos Philopator became co-ruler in 147 BC. Following his father's death, he ruled from about July to late August 145, with the support of Cleopatra II. His father's army, however, had been dispersed in Syria; and Neos Philopator and his mother enjoyed only limited support. After the opposition factions invited the young king's uncle, Ptolemy VIII, to assume the kingship, Neos Philopator was deposed. He was executed the following year, after his uncle married his mother.