In Greek mythology, Thestius was a king of the Pleuronians in Aetolia. He is best known as the father of Althaea (mother of the hero Meleager) and Leda (mother of Helen, Clytemnestra, and the Dioscuri), making his house a bridge between Calydonian Aetolia and the royal line of Sparta. His parentage is given variously across the ancient sources, and he should not be confused with Thespius, who is occasionally called by the same name.
Adapted from Wikipedia, "Thestius" · CC BY-SA 4.0
I.Identity
In Greek mythology, Thestius (Ancient Greek: Θέστιος, romanized: Théstios) was a king of the Pleuronians in Aetolia.
He should not be confused with Thespius, who was occasionally called by the same name. The patronymic "Thestias" may refer to one of his daughters, Leda or Althaea, while "Thestiades" refers to his son Iphiclus.
II.Family
Thestius was the son either of Ares by Demonice or Pisidice, or of Agenor (son of Pleuron), possibly by Epicasta. He was the brother of Evenus, Pylus and Molus, or alternatively of Demonice and Porthaon.
Thestius was the father of Iphiclus by Leucippe or by Eurythemis, daughter of Cleoboea, who was the mother of his other children: Althaea, Eurypylus, Evippus, Hypermnestra, Leda and Plexippus. In other sources the mother of Iphiclus, Althaea and Leda is named either Laophonte, daughter of Pleuron, or Deidameia, daughter of Perieres. Other sons attributed to Thestius were Cometes and Prothous, Toxeus, Aphares and Calydon.
III.Mythology
Thestius allied himself with Tyndareus and Icarius against Hippocoon. According to Strabo, after they had been banished, Tyndareus and Icarius sought the aid of Thestius. The king helped them acquire territory beyond the Acheloüs River, in exchange for a share in its possession. Tyndareus then married Leda, the daughter of Thestius, and departed, while Icarius remained behind in Acarnania.
In a rare variant preserved by Plutarch, Thestius travelled to Sicyon and, on his return home, found his son Calydon together with his mother. Believing that infidelity had taken place, he killed his own son. When he realised his error, he cast himself into the river Axenos, which thereafter bore his name.