Adrastus (Ancient Greek: Ἄδραστος, Adrastos) or Adrestus (Ionic Ἄδρηστος, Adrēstos), traditionally translated as "nonparticipant" or "uncooperative", was a legendary king of Argos during the war of the Seven Against Thebes.

He was a son of Talaus and Lysimache.Pausanias calls his mother Lysianassa, and Hyginus calls her Eurynome. He was one of the three kings at Argos, along with Iphis and Amphiaraus, the husband of Adrastus's sister Eriphyle. He was married either to Amphithea, daughter of Pronax, or to Demonassa. His daughters Argea and Deipyle married Polynices and Tydeus, respectively. His other children include Aegiale, Aegialeus, and Cyanippus.

During a feud between the most powerful houses in Argos, Talaus was slain by Amphiaraus, and Adrastus being expelled from his dominions fled to Polybus, then king of Sicyon. When Polybus died without heirs, Adrastus succeeded him on the throne of Sicyon, and during his reign he is said to have instituted the Nemean Games.

According to "Gods and Goddesses of Ancient Greece" by Edward E. Barthell, he states that Adrastus is the son of Talaus and Lysimache (daughter of Abas). He married Amphitheia, daughter of his brother Pronax, and became the father of a son, Aegialeus, and four daughters: Aegialeia, who became the wife of Diomedes (son of Tydeus); Argeia, who became the wife of Polyneices (son of Oedipus); Deipyle, who became the wife of Tydeus (son of Oeneus); and Eurydice, who became the wife of the Trojan king, Ilus (son of Tros).