Ethnarch, pronounced //, the anglicized form of ethnarches (Greek: ἐθνάρχης) refers generally to political leadership over a common ethnic group or homogeneous kingdom. The word is derived from the Greek words ἔθνος (ethnos, "tribe/nation") and ἄρχων (archon, "leader/ruler").
The title first appears in the Hellenistic Middle East, possibly in Judea. It was used in the region even after it fell under the dominion of Rome, and until the early Roman Empire, to refer to rulers of vassal kingdoms who did not rise to the level of kings. The Romans used the terms natio and gens for a people as a genetic and cultural entity, regardless of political statehood.
The best-known is probably Herod Archelaus, son of Herod the Great, who was ethnarch of Samaria, Judea (Biblical Judah), and Idumea (Biblical Edom), from the death of his father in 4 BC to AD 6. This region is known as the Tetrarchy of Judea. His brother Philip received the north-east of the realm and was styled Tetrarch (circa 'ruler of a quarter'); and Galilee was given to Herod Antipas, who bore the same title. Consequently, Archelaus' title singled him out as the senior ruler, higher in rank than the tetrarchs and the chief of the Jewish nation; these three sovereignties were in a sense reunited under Herod Agrippa from AD 41 to 44.
Byzantine Empire 
The Byzantines used the term generically to refer to the rulers of barbarian tribes or realms outside the boundaries of their empire. In a Christian context, were ethnikos meant "pagan", some Church Fathers used the term ethnarches to designate pagan national gods. In the 10th century, the term acquired a more technical sense, when it was given to several high-ranking commanders. Although the specific nature of the title is not attested, it is generally accepted that in the 10th-11th centuries, it signified the commanders of the contingent of foreign mercenaries serving in the Byzantine army.
Ottoman Empire 
Rather different was the case of minority community ethnarchs, especially within the Islamic Ottoman Empire (political successor to Byzantium) that were recognized as legitimate entities (millet) and thus allowed to be heard by the government through an officially acknowledged representative, though without political persona.
When the Ottoman Sultan Mehmet II decided to give such dialogue a more formal nature, the logical choice for the major Orthodox Christian communities was the Greek Orthodox Ecumenical Patriarch of Constantinople. The non-Chalcedonian Christians (Armenians, Syriacs, and Copts) were represented by the Armenian Patriarchate of Constantinople. For the far smaller, but also influential Jewish diaspora, a similar position was granted to the Hakham Bashi, i.e., chief rabbi.
Modern Greece 
In modern Greek usage, the term has the connotation of "father of the nation", and is widely used as an epithet applied to the most influential political leaders of modern Hellenism: Eleftherios Venizelos, Archbishop Makarios (for Cyprus), and sometimes Konstantinos Karamanlis.
- Kazhdan (1991), p. 734
- Yilmaz, Hakan; Aykaç, Çagla E (2012), Perceptions of Islam in Europe: Culture, Identity and the Muslim 'Other', I.B.Tauris, p. 82, ISBN 9781848851641 Text "book " ignored (help)
- ΣΥΓΧΡΟΝΗ ΕΛΛΗΝΙΚΗ ΠΟΛΙΤΙΚΗ ΚΑΙ ΣΥΝΤΑΓΜΑΤΙΚΗ ΙΣΤΟΡΙΑ 1940-1986 ΑΝΑΣΤΑΣΙΑΔΗΣ ΓΙΩΡΓΟΣ p. 149