Aegialeus, the king of Sicyon, was thought to be the first settler in the region of the Peloponnese, and founder of the city of Sicyon. He was one of the sons of the river god Inachus, who later founded the city of Argos, and the Oceanid Melia.
Aegialeus, the king of Argos, was the son of Adrastus and Amphithea; his father participated in the attack of the city of Thebes as described in the play of Seven Against Thebes, which ended in the defeat of the attackers. Aegialeus, among others, launched a second attack against the city, successfully capturing it, but was also the only one who died in the battle.
Finally, Aegialeus is another name given to Absyrtus, son of Aeetes and brother of Medea, who killed him and threw his body parts in the water, in an attempt to stall their father who was pursuing her and Jason.