In Greek mythology, Adrastus or Adrestus (Ancient Greek: Ἄδραστος or Ἄδρηστος), (perhaps meaning "the inescapable"), was a king of Argos, and leader of the Seven against Thebes. He was the son of the Argive king Talaus, but was forced out of Argos by his dynastic rival Amphiaraus. He fled to Sicyon, where he became king. Later, he reconciled with Amphiaraus and returned to Argos as its king.
Because of an oracle, Adrastus married his daughters to the exiles Polynices and Tydeus and promised to restore them to their homelands. He first assembled an army to place Polynices on the throne of Thebes, led by seven champions, famously called the Seven against Thebes. The expedition failed, and all the champions died except Adrastus, saved by his divine horse Arion. He went with the Epigoni, the sons of the Seven, in the successful second war against Thebes, and was said to have died on his way home.