A son of Pelias, king of Iolcus, and of Anaxibia, or as others call her, Philomache. He was one of the Argonauts,1 and also took part in the Calydonian Hunt.2

After the return of the Argonauts his sisters were seduced by Medea to cut their father in pieces and boil them; and Acastus, when he heard this, buried his father, drove Jason and Medea, and according to Pausanias3 his sisters also, from Iolcus, and instituted funeral games in honor of his father.4

During these games it happened that Astydameia, the wife of Acastus, who is also called Hippolyte, fell in love with Peleus, whom Acastus had purified from the murder of Eurytion. When Peleus refused to listen to her addresses, she accused him to her husband of having attempted to dishonor her.5 Acastus, however, did not take immediate revenge for the alleged crime, but after he and Peleus had been chasing on Mount Pelion, and the latter had fallen asleep, Acastus took his sword from him, and left him alone and exposed, so that Peleus was nearly destroyed by the centaurs. But he was saved by Chiron or Hermes, returned to Acastus, and killed him together with his wife.6

The death of Acastus is not mentioned by Apollodorus, but according to him Peleus in conjunction with Iason and the Dioscuri merely conquer and destroy Iolcus.7