Acacus (Ἄκακος - Harmless), in Greek mythology, was a king of Acacesium (Ἀκακήσιον) in Arcadia, the son of Lycaon, and the foster-father of the infant Hermes.
Maia gave birth to Hermes at dawn in a sacred cave on Mount Cyllene in Arcadia, and he was raised by Acacus. He was believed to be the founder of the Arcadian town of Acacesium where he was king.
- ^ Pausanias. Description of Greece, viii. 3. § 1;