In Greek mythology, Acastus was a king who sailed with the Argonauts, a group of adventurers seeking a famous treasure called the Golden Fleece. Jason, his fellow Argonaut, brought a witch named Medea to Acastus's kingdom of Iolcus. There Medea tricked the king's sisters into murdering their father. Discovering this treachery, Acastus drove Jason and Medea from his kingdom.
Acastus held funeral games in honor of his murdered father. Among the guests was his friend Peleus, another Argonaut. Acastus's wife, Hippolyte (or in some versions Astydameia), fell in love with Peleus but was rejected by him. Hurt and angry, she told Acastus that Peleus had made advances to her. Acastus decided to take his friend hunting and steal his sword, leaving him to be killed by wild centaurs. However, Peleus survived. Later he conquered Iolcus and killed both Acastus and his wife.
centaur half-human, half-animal creature with the body of a horse and the head, chest, and arms of a human