An exarch is an official in various jurisdictions both historical and modern.
Georgian Exarchate in the 19th century
Metropolitan Platon (Rozhdestvensky), last Exarch of Georgia (1915–1917) and first Exarch of Caucasus (1917–1918)
A viceroy is an official who reigns over a polity in the name of and as the representative of the monarch of the territory.
Exarch
…thus formed in the western regions of the empire: the Exarchate of Ravenna and the Exarchate of Africa, both headed by imperial exarchs with extensive viceroyal powers. The creation of such a powerful office was a response to the need of strengthening imperial authority in remote regions of the empire. It was…
Cindy Kiro (centre), the governor-general of New Zealand, with Executive Council members in 2023, in front of the portrait of Elizabeth II, Queen of New Zealand.
A watercolor of a procession in Mexico City of the Viceroy of New Spain, ca. 1821
Joaquín de la Pezuela, penultimate viceroy of Peru
"Roy" Edward III, King of England. Bruges Garter Book.