Ptolemy VI (Ptolemy Philometor) (tŏl´əmē fĬləmē´tər), d. 145 BC, king of ancient Egypt (180–145 BC), of the Macedonian dynasty, son of Ptolemy V. He became king when an infant, and his mother, Cleopatra, was regent. After her death, Antiochus IV of Syria invaded Egypt, and Ptolemy was captured (170 BC) at Pelusium. He was forced to share the rule with his wife (also his sister), Cleopatra, and his brother, Ptolemy Physcon (later Ptolemy VIII). Ptolemy Physcon ruled over Cyrene, Ptolemy Philometor over Egypt; trouble between the brothers ultimately caused the intervention of Rome. Ptolemy VI aided Demetrius II to gain the throne of Syria and was killed in battle with the rival claimant, Alexander Balas. His young son in theory succeeded to the throne and is usually called Ptolemy VII, but he was put to death as soon as Ptolemy Physcon (who is sometimes counted as Ptolemy VII) could reach Egypt.