Adrastus was the king of Argos in Greek mythology, who participated in the war of the Seven Against Thebes. His parents were Talaus and Lysimache. He co-reigned in the city of Argos, along with Iphis and Amphiaraus.
After a power clash between the major houses of Argos, Adrastus' father was murdered by Amphiaraus, and Adrastus had to flee; he found refuge in the city of Sicyon, at the court of Polybus. Polybus died childless, and Adrastus took his place on the throne. Years later, Adrastus and Amphiaraus left their differences aside, and Adrastus returned to Argos. During his co-reign, Tydeus and Polynices arrived at his court, who started quarreling. Adrastus tried to stop the fight and realised that this was a prophecy he had received earlier from an oracle; he was told to marry his daughters to a boar and a lion, the respective figures on Tydeus' and Polynices' shields. Polynices married Argeia, while Tydeus married Deipyle, and Adrastus promised his sons-in-law to help them go back to their country.
Despite Amphiaraus' warning that this would end badly, Adrastus created an army, and was joined by six more leaders, Polynices, Tydeus, Amphiaraus, Capaneus, Hippomedon, and Parthenopaeus. This commenced the war of the Seven Against Thebes, which ended in the demise of the attackers. Only Adrastus was saved thanks to the agility of his flying horse, Arion. Ten years later, Adrastus persuaded the sons of the fallen to attack Thebes again. This time, Amphiaraus was told by the gods that the attack would have a positive outcome. This war was known as the War of the Epigoni and resulted in the raid of Thebes. During the raid, Adrastus' son, Aegialeus, was the only hero that died. Adrastus built a monument in the name of Nemesis, goddess of retribution and revenge, and started his journey home. Before reaching Argos, though, he died of grief for his son's death.