Abderus was a hero in Greek mythology, one of the lovers of the demigod hero Heracles, and son of the god Hermes. According to other sources, he was the son of Thromius; Opian Menoetius, one of Heracles' friends; or Poseidon and Thronia.
He participated in the eighth of the Labours of Heracles, in which he helped his friend capture the Mares of Diomedes. During the task, Heracles lured the fearsome Mares (who ate human flesh) onto a peninsula, and then created a ditch of water, effectively forming a small island. He then told his friend Abderus to take care of the animals, while he hunted down the army of Diomedes. When he returned triumphantly, he found out that Abderus had been eaten by the horses; furious, Heracles fed their master to them, and then founded the city of Abdera in commemoration of his friend. He also founded athletic games in his honour.