Achaemenes. I. The ancestor and founder of the Achaemenidae, the noblest family of the Pasargadaae, and from the time of Cyrus (third in descent from him, according to Herodotus) the royal family of Persia. In Latin poetry, Achwmenius is often used as a synonyme for Persicus, Persian.

II. Son of Darius I., and brother of Xerxes, was made by the latter satrap of Egypt in 484 B. C, and accompanied him in his expedition against Greece in 480, when he commanded the Egyptian fleet. He fell in Egypt in 460, in an unsuccessful attempt to quell the revolt of Inarus, a Libyan chief.