Diomedes (Brazilian Portuguese) or Diomedes (European Portuguese) (Greek: Διομήδης, meaning "skilled as a god") was a giant, son of the god Ares and Cyrene, a nymph from Thessaly. He was king of a people of warriors who inhabited Thrace, on the shores of the Black Sea.
The mares of Diomedes
Diomedes is especially known in Greek mythology for his four violent and untamed mares - Podargo the "bright-footed", Lampon the "resplendent", Janto the "yellow", and Deino the "terrible" - who terrorized the entire region by feeding on human flesh.
In the eighth of his famous works, in response to a demand from Eurystheus, Heracles set out with a group of volunteers to capture the mares. Having overpowered the animals, he was attacked on the shore by Diomedes and his Thracian warriors.
To fight them off, Heracles left the mares in the care of his eromenos, Abdero, son of the god Hermes. Heracles won the fight and trapped Diomedes, but Abdero was attacked and eaten by the mares. In honor of his companion, Heracles founded the city of Abdera on the coast. Diomedes was killed by Heracles, or according to some traditions, abandoned to be devoured by the mares themselves.
Heracles took the mares to Mycenae and gave them to Eurystheus. Through an oversight of Eurystheus' servants, the mares managed to escape and headed north to Thessaly. Finally, they climbed Mount Olympus, where they were eventually devoured by wild animals.