Acastus- Greek HeroHero"King of Iolcus"

Son of Pelias

Acastus was the son of King Pelias of Iolcus, who had seized the throne from his half-brother Aeson and sent Aeson's son Jason after the Golden Fleece expecting him to die. Acastus defied his father and joined the Argonauts, sailing alongside Jason himself. When they returned, Medea tricked Pelias's daughters into killing their own father. Acastus drove Jason and Medea from Iolcus, took the kingship, and held funeral games for Pelias that drew heroes from across Greece.

The Betrayal of Peleus

After Peleus accidentally killed Eurytion during the Calydonian Boar Hunt, he came to Iolcus seeking purification from blood-guilt, which Acastus granted. But Acastus's wife — Astydameia in Pindar's account, Hippolyte in others — desired Peleus, and when he rejected her, she struck first at his family. She sent word to Peleus's wife Antigone in Phthia that Peleus planned to marry Acastus's daughter Sterope. Antigone hanged herself on the false report. Then Astydameia told Acastus that Peleus had tried to force himself on her.

The Abandonment on Mount Pelion

Acastus could not kill his guest outright without violating the sacred laws of hospitality. He took Peleus hunting on Mount Pelion instead and, while Peleus slept, stole his sword — a divine blade forged by Hephaestus — and hid it in a dung heap. Then he left, abandoning Peleus unarmed in centaur country. The wise centaur Chiron found the hidden sword and returned it to Peleus, saving his life.

Aftermath

Peleus returned to Iolcus with Jason and the Dioscuri at his side and sacked the city. Apollodorus records that he killed Astydameia and marched his troops through her dismembered body into the gates. Acastus was driven into exile. In a later generation, his sons regained Iolcus and expelled the aged Peleus, only to be defeated by Peleus's grandson Neoptolemus after the fall of Troy.