Acacus (Ancient Greek: Ἄκακος or Ἄκακον means 'harmless, guileless'), in Greek mythology, was a king of Acacesium (Ἀκακήσιον) in Arcadia. He was one of the 50 sons of the impious King Lycaon[1] either by the naiad Cyllene,[2] Nonacris[3] or by unknown woman. Acacus was the foster-father of the infant Hermes.[4]
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.[5]