The Clergy of the Orthodox church are set apart through the Sacrament of Ordination or the "laying-on-of hands" and are divided into three orders:

1. Deacons
2. Presbyters or Priest (hiereas)
3. Bishops (Episkopos)

An Orthodox presbyter is either married (usually serving as a parish priest) or celibate, generally belonging to a monastic order (hieromonachos) called "Archimandrite". Bishops are usually chosen from the ranks of the Archimandrites.

An Orthodox bishop, depending on his jurisdiction and rank, may be called Bishop (usually auxiliary to an Archbishop); Metropolitan (head of a large city or a Diocese); Archbishop (head of an Orthodox country or capital city); Patriarch (head of an ancient or ethnic Church). The bishops of the ancient Sees of Rome and Alexandria are also called Popes. Orthodox clergy of all orders wear the cassock (rasso) in public, but when participating in a church service wear the the vestment of their own order and rank. In some Balkan countries(including Greece) they also wear a black cylinder-like hat (kalimafi) on top of which the celibates (except deacons) wear a black veil dropping down the back (Epanokalimafkon).

The form of address for Orthodox clergy varies according to order, rank, and level of education. The most common forms are the following:

Gr. = Greek        Sl. = Slavonic