These vary considerably according to the country, but the following is good English usage for
(1) addressing a etc.,
(2) beginning a letter and in its body,
(3) personal speech.

Many of the forms are, of course, modified by the occasion and the degree of acquaintanceship.

A POPE.
(1) His Holiness Pope N-----.
(2) Most Holy Father; your Holiness; Prostrate at the feet of your
Holiness, I have the honor to profess myself with the most profound
respect, your Holiness's most obedient and humble servant ------.
(3) Your Holiness.

CARDINALS.
(1) His Eminence Cardinal N-----
(2) My Lord Cardinal; your Eminence; I have the honor to be, with great
respect, your Eminence's most obedient and humble servant -----
(3) Your Eminence.
If he is an archbishop or bishop:
(1) His Eminence the Cardinal Archbishop of -----, or His Eminence = Cardinal
N-----, Archbishop of -----. The rest as above.

PATRIARCHS, EASTERN.
(1) His Beatitude (or Blessedness) the Patriarch of -----, or His = Beatitude
the Lord (Christian name), Patriarch of -----.
(2) Most Reverend Lord; your Beatitude; I have the honor to be your
Beatitude's obedient servant -----.
(3) Your Beatitude.

PATRIARCHS, LATIN TITULAR, AND NUNCIOS.
(1) His Excellency the Patriarch (Archbishop) of, or His Excellency
Monsignor N-----, Patriarch (Archbishop) of -----.
(2) My Lord Patriarch (Archbishop) or Most Reverend Excellency; your
Excellency; I have the honor to be your Excellency's obedient servant -----.
(3) Your Excellency.

ARCHBISHOPS.
(1) His Grace the Archbishop of -----, or The Most Reverend A----- = B-----,
Archbishop of -----.
(2) My Lord Archbishop or My Lord; your Grace; I have the honor to be = your
Grace's obedient servant -----.
(3) Your Grace.

BISHOPS.
(1) The Lord Bishop of -----, or The Right Reverend A----- B-----, Bishop
of -----.
(2) My Lord Bishop or My Lord; your Lordship; I have the honor to be your
Lordship's obedient servant -----.
(3) My Lord.

Bishops in Ireland are Most Reverend; the style Lord, Lordship, etc., is not generally used in the United States for archbishops, bishops, or abbots.

Titular Archbishops and Bishops. These are best addressed in exactly the same way as diocesan prelates, but their office may be added, e.g., The Right Reverend A----- B-----, Vicar Apostolic of

On the use of the title Monsignor (to which all bishops are entitled) and of bishop as a prefix, see within under Monsignor.

ABBOTS.
(1) The Lord Abbot of ----- or The Right Reverend Dom A----- B-----, = O.S.B.
(or otherwise), Abbot of -----.
(2) My Lord Abbot or Dear Father Abbot.
(3) My Lord or Father Abbot. Abbesses similarly, substituting Lady = Abbess,
Dame and Mother.

PROTONOTARIES APOSTOLIC, DOMESTIC PRELATES, VICARS GENERAL.
(1) The Right Reverend Monsignor A----- B-----, Prot. Ap., or V.G.
(2) Right Reverend Monsignor or Dear Monsignor N-----.
(3) Monsignor.

PROVOSTS, CANONS.
(1) The Very Reverend Provost A----- B-----. The Very Reverend Canon = A-----
B-----. The Very Reverend A-----, Canon B----- is a common usage.
(2) Very Reverend Provost, Dear Canon N-----.
(3) Provost, Canon.

PAPAL CHAMBERLAINS.
(1) The Very Reverend Monsignor A----- B-----.
(2) Very Reverend Monsignor or Dear Monsignor N-----.
(3) Monsignor.

Rectors of Seminaries, Heads of Colleges, etc., are commonly addressed as The Very Reverend A----- B-----.

PROVINCIALS OF RELIGIOUS ORDERS.
(1) The Very Reverend Father Provincial , O.F.M. (or otherwise), or The
Very Reverend Father A----- B-----, Provincial S.J.
(2) Very Reverend Father or Dear Father Provincial.
(3) Father Provincial.

CONVENTUAL PRIORS AND THEIR EQUIVALENTS.
(1) The Very Reverend the Prior of ----- or The Very Reverend Father (or
Dom, see below) A----- B----- O.P. (or otherwise), Prior of -----. The = Very
Reverend Father Guardian, O.F.M.
(2) Very Reverend Father or Dear Father Prior.
(3) Father Prior. Prioresses similarly, substituting Prioress, Mother, = Dame
(if required).

CLAUSTRAL PRIORS.
(1) The Very Reverend Dom A----- B-----, O.C. (or otherwise) or The Very
Reverend Father Prior, ----- Abbey.
(2) Very Reverend Father or Dear Father Prior.
(3) Father Prior.

ARCHDEACONS.
(1) The Venerable the Archdeacon of ----- or The Venerable A----- B-----, Archdeacon of

There are no archdeacons and no deans, properly so called, in England. Rural Deans are addressed as The Very Reverend A----- B-----, R.D., or = V.F.

PREACHERS GENERAL.
(1) The Venerable and Very Reverend Father A----- B-----, O.P., P.G.

PRIESTS, SECULAR.
(1) The Reverend A----- B-----.
(2) Reverend Sir or Dear Father N-----.
(3) Father. For this usage of Father, see within under that word.

PRIESTS, REGULAR.
(1) The Reverend Father A----- B-----, O.S.M. (or otherwise; and see below).
(2) Reverend Father or Dear Father N. (Christian name).
(3) Father. Benedictine and Cistercian monks and Canons Regular are
addressed Dom, thus: The Reverend Dom A----- B-----, C.R.L. (or otherwise)= ,
but in speech as Father; Carthusian monks as The Venerable Father Dom
A----- B-----, O.Cart.

CLERICS BELOW THE ORDER OF PRIESTHOOD.
(1) The Reverend A----- B-----.
(2) Reverend Sir or Dear Mr. N-----.
(3) Mr. N-----. The Style of clerics who are members of religious orders = is
modified according to their status in the order.

[From "A Catholic Dictionary", Attwater. (1954)]

Prayer From:
THE VOTIVE MASS OF OUR LORD JESUS CHRIST,
THE MOST HIGH AND ETERNAL PRIEST

O God, who unto the glory of Thy majesty and the salvation of the human
race hast ordained Thy only begotten Son a Priest Most High and Eternal:
grant that those ministers and dispensers of His mysteries whom He hath
chosen may be found faithful in fulfilling the ministry which they have
accepted. Through the same Jesus Christ our Lord. Amen.