(ἐξάρχος, a chief person or leader), a title that has been conferred at different periods on certain chief officers or governors, both in secular and ecclesiastical matters. Of these, the most important were the exarchs of Ravenna. The first of these was appointed by Justinian, emperor of the East, as governor of the middle part of Italy, which was made a province of the Eastern empire after Naras had entirely subdued the Goths and their allies in Italy, A.D. 552-554. Ravenna, with the whole exarchate, was conquered by Astolpus, king of the Lombards, in the year 752; but three years later it was taken by Pepin, king of the Franks, who bestowed it on the pope (Stephen III.),—since which time Ravenna and its territory have remained united to the papal dominions.

EXARCH of a Diocese was, anciently, the same with primate. This dignity was intermediate between the patriarchal and the metropolitan. Exarch is also used, in the ecclesiastical antiquities of the Eastern Church, for a general or superior over several monasteries.

In the modern Greek Church, an exarch is a deputy or legate a latere of the patriarch, whose office it is to visit the clergy and churches in the provinces allotted him. The power which the exarch enjoys, and the uses to which he turns it, recall the times of the corrupt processuals of the Roman empire. He usually enriches himself greatly in his post, and frequently rises to the patriarchate itself.