In Greek mythology, Tydeus was the father of Diomedes and husband of Deipyle. He was a son of Oeneus and Periboea. He was one of the Seven Against Thebes; during the battle to take the city, he was killed by Melanippus.

In the Iliad, Homer makes such frequent and detailed references to the exploits of Tydeus (in connection with his son) that some commentators have speculated that Homer must have composed another work having Tydeus as its main subject.