Antigonus III Doson
Demetrius's first marriage was to an Olympias, a Greek noblewoman from Larissa, the daughter of a nobleman, Polycletus or Polyclitus of Larissa. She probably died before 249 BC. Their children were Antigonus III Doson, the later Macedonian King, and Echecrates, a nobleman about whom not much is known apart from the fact that he had a son whom he named after his brother Antigonus. A few months before his paternal second cousin King Philip V of Macedon’s death, Echecrates' son Antigonus revealed to Philip that Philip's son, the prince Perseus of Macedon, had made false accusations against his brother, Philip's other son, Demetrius, whom Philip had then had put to death. Philip, indignant at Perseus’ conduct appointed Antigonus as his successor. When Philip died in 179 BC and Antigonus became king, Perseus ousted Antigonus and had him executed.