In Greek mythology, Abderus or Abderos (Ancient Greek: Ἄβδηρος, romanized: Ábdēros) was a divine hero, reputed by some to be one of Heracles' lovers (eromenoi), and reputedly a son of Hermes by some accounts, and eponym of Abdera, Thrace.

Some sources say he was the son of the god Hermes and a native of Opus in Locris, and according to other writers, he was the son of Thromius the Locrian. Pindar makes Abderus a son of Poseidon and Thronia, while Photius writes that he was brother of Patroclus, and according to Hellanicus (who considers him the son of Hermes), he was Heracles' lover.

Abderus was mostly known for his tragic role in Heracles' Eighth Labor. Along with others, he helped Heracles capture the four savage mares of Diomedes the king of the Thracian Bistones. Heracles overpowered the grooms and drove the Mares of Diomedes into the sea and left them in the care of Abderus. However, while Heracles was away, the horses devoured Abderus. In revenge, Heracles fed Diomedes alive to his own mares.

Heracles was heartbroken upon Abderus's death, weeping, hugging and wailing over what remained of his lover. Heracles buried Abderus in a cermonial tomb, with a bowl containing a kalos inscription of affection. Heracles then founded the city of Abdera near Abderus's tomb, where agones (Greek: ἀγῶνες), athletic games consisting of boxing, pancratium and wrestling were held in his honor (but chariot races were banned in respect of how he died).

In some very different traditions, instead of helping Heracles with his Eighth Labor, Abderus (or Abdertis) was a servant of Diomedes, and was killed by Heracles together with his master and his four men-devouring horses.