(Ἀκάδημος), an Attic hero, who, when Castor and Polydeuces invaded Attica to liberate their sister Helen, betrayed to them that she was kept concealed at Aphidnae. For this reason the Tyndarids always showed him much gratitude, and whenever the Lacedaemonians invaded Attica, they always spared the land belonging to Academus which lay on the Cephissus, six stadia from Athens. (Plut. Thes. 32; D. L. 3.1.9.) This piece of land was subsequently adorned with plane and olive plantations (Plut. Cim. 13), and was called Academia from its original owner.