Antalcidas () was a Spartan soldier and diplomat, the son of Leon. In 393 (or 392) BC he was sent to Tiribazus, Persian satrap of Sardis, to undermine the friendly relations then existing between Athens and Persia, offering to recognize Persian claims to the whole of Asia Minor and supremacy over Greek cities there. The Athenians sent an embassy under Conon to counteract his efforts. Tiribazus, who was favourable to Sparta, threw Conon into prison, but Artaxerxes II (Mnemon) disapproved and recalled his satrap.