Diomedes (/ˌdaɪəˈmiːdiːz/ ) or Diomede (/ˈdaɪəmiːd/; Ancient Greek: Διομήδης, romanized: Diomēdēs, lit. 'god-like cunning" or "advised by Zeus') is a hero in Greek mythology, known for his participation in the Trojan War.
He was born to Tydeus and Deipyle and later became King of Argos, succeeding his maternal grandfather, Adrastus. In Homer's Iliad Diomedes is regarded alongside Ajax the Great and Agamemnon, after Achilles, as one of the best warriors of all the Achaeans in prowess. After the Trojan War he is said to have founded ten or more Italian cities and, after his death, was worshiped as a divine being in both Italy and Greece.