ETHNARCH (formed of εθνος, nation, and ἄρχω, command), a governor or ruler of a nation.

There are some medals of Herod surnamed the Great, on one side of which is found Ἡρῴδης, and on the other Ἐθνάρχης, or Herod the Ethnarch. After the battle of Philippi, Antony passed into Syria, constituted Herod and Phasael his brother tetrarchs, in which quality he committed to them the administration of the affairs of Judæa. Herod therefore had the government of the province before the Parthians entered Syria, or before the invasion of Antigonus, which did not happen till six or seven years after Herod commanded in Galilee. Herod was, therefore, truly ethnarch, for he cannot be otherwise denominated; so that it must have been during that period the medals were struck which gave him this title; and these medals are a confirmation of what we read in history of the government which that prince was intrusted with before he was raised to royal state. Josephus gives Herod the appellation of tetrarch instead of that of ethnarch; but the two terms come so near to each other, that it is easy to confound them together. Though Herod the Great left by will to Archelaus all Judæa, Samaria, and Idumæa, yet Josephus tells us he was then only called ethnarch.