Also known as Seoán Ó Laithim. Formerly Archdeacon of Killala. Elected bishop on 13 June 1306 and received possession of the temporalities after that date, and consecrated circa 1307. Died in office.
Also known as William O'Dowda. Elected in 1344, appointed on 26 June 1346, and received possession of the temporalities on 25 March 1348. Died in office.
Also known as Cornelius. Formerly a canon of Tuam. Appointed by Antipope Clement VII before 19 February 1383. Not known when his episcopate ended, but died in 1422 or 1423.
1390
1398
Thomas Orwell, O.F.M.
Also known as Thomas Horwell. Appointed on 31 January 1390. Acted as a suffragan bishop in the dioceses of Ely and Norwich 1389–1406. Translated to Dromore before November 1398.
1398
1400
See vacant
1400
1425
Tomás mac Uilliam Duibh Bairéad
Also known as Thomas Barrett or 'an t-easbog Tóimineach'. Appointed before 14 April 1400 and received possession of the temporalities on 12 March 1401. Died in office on 25 January 1425.
c. 1403
(Muircheartach Cléirach mac Donnchadha Ó Dubhda)
Elected circa 1403, but was never consecrated, and died later in the same year.
1425
1431/32
Fearghal Ó Martain, O.E.S.A.
Appointed on 26 September 1425 and consecrated on 11 November 1427. Died in office on 30 January 1431 or 1432.
1431
Thaddaeus 'Mac Creagh'
Appointed, by provision of the Pope; and was pardoned for accepting the appointment, and was admitted to all the privileges of an English subject, by King Henry VI in September 1431.
1432
1436
Brian Ó Coineóil
Also known as Bernardus. Appointed on 30 January 1432. Deposed in 1436.
1436
1436
Maghnus Ó Dubhda
Formerly Archdeacon of Killala. Elected bishop in 1436. Died in office on 22 February 1436.
1436
1439
See vacant
1439
1461
Brian Ó Coineóil (again)
Restored in 1439. Murdered on 31 May 1461 by the son of Bishop Maghnus Ó Dubhda.
1447
(Robert Barrett)
Provost of Killala. Appointed bishop on 3 July 1447, but did not take effect.
1452
(Ruaidhrí Bairéad, O.E.S.A.)
Also known as Rory Barrett. Appointed on 3 March 1452, but did not take effect. Died after May 1458.
1453
(Thomas)
Appointed before 7 January 1453, but did not take effect.
1459
(Richard Viel, O.Carth.)
Prior of Witham Friary. Appointed on 17 October 1459, but did not take effect.
1461
1467
Donatus Ó Conchobhair, O.P.
Formerly a friar of Rathfran (a friary north of Killala). Appointed on 2 December 1461. Died in office after 1467.
Also known as Tomas Bairéad. Formerly a canon of Crossmolina. Appointed bishop on 9 February 1470. Acted as a suffragan bishop in the English Diocese of Ely in 1497. Died after 1497.
1487
1490
Seaán Ó Caissín, O.F.M.
Also known as John O'Cassin and Johannes de Tuderto. Appointed bishop on 18 January 1487. Resigned in 1490.
1490
1500
See vacant
1500
1505
Thomas Clerke
Also known as Thomas Cleragh. Formerly Archdeacon of Sodor (Isle of Man). Appointed bishop on 4 May 1500. Resigned in 1505, becoming Rector of Chedsey in Somerset, where died there in 1508.
1505
1508
See vacant
1508
bef.1513
Malachias Ó Clúmháin
Formerly a priest of the Diocese of Clonfert. Appointed on 12 February 1506 and consecrated on 3 September 1508. Died in office before 1513.
Also known as Risdéard Bairéad. Formerly a canon of Killala. Appointed bishop by Pope Julius II on 7 January 1513. Not known if Barrett acknowledged Royal supremacy. Died in office before 6 November 1545.
Appointed by Pope Paul III on 6 November 1545 and presumably recognized by the crown in the reign of Queen Mary I. Translated to the Roman Catholic see of Derry by Pope Pius V on 22 June 1569. Described by the papal legate Fr David Wolfe SJ as 'as strong as [a] bulwark of the Bride of Christ' in an account of approximately 1573[17]
Appointed by papal bull on 6 February 1645 (N.S.) and consecrated at Paris on 7 May 1645 (N.S.). Returned to Ireland, but following the fall of Galway in 1651, he hid from Parliamentarian troops for many months, eventually imprisoned in Galway and then banished to France in August 1655. Died in exile at Rennes on 27 August 1661.[26]
1661
1671
See vacant
1671
unknown
(John Burke, vicar apostolic)
Also recorded as John de Burgo. Appointed vicar apostolic on 16 May 1671 (N.S.) and papal brief issued on 30 June 1671 (N.S.).
1676
unknown
(John Dooley, vicar apostolic)
Appointed vicar apostolic on 22 April 1676 (N.S.).
Also known as Tadhg O'Rourke. Appointed on 15 November 1703 (N.S.) and again on 15 March 1707 (N.S.). Consecrated on 24 August 1707. Died in office before September 1735.
Appointed coadjutor bishop (with right of succession) on 20 February 1825, papal brief issued on 8 March 1825, and consecrated on 5 June 1825. Succeeded diocesan bishop on 27 May 1834. Translated to Tuam on 21 July 1834.
Appointed on 1 February 1835, papal brief issued on 13 February 1835, and consecrated 21 March 1835. Allowed to retain the title Bishop of Killala on 19 November 1838, but was deprived jurisdiction of the Diocese of Killala. Died on 27 November 1847.
Also known as Thomas Feeny. Appointed Papal Administrator of Killala on 18 July 1839 and consecrated Titular Bishop of Ptolemais in Phoenicia on 13 October 1839. Appointed Diocesan Bishop of Killala on 12 December 1847 and papal brief issued on 11 January 1848. Died in office on 9 August 1873.
Appointed coadjutor bishop (with right of succession) on 21 November 1871 and consecrated on 4 February 1872. Succeeded diocesan bishop on 9 July 1873. Died in office on 23 April 1893.
Appointed coadjutor bishop (with right of succession) on 25 May or June 1892 and consecrated on 24 August 1892. Succeeded diocesan bishop on 23 April 1893. Died in office on 26 August 1911.
Cotton, Henry (1850). The Province of Connaught. Fasti Ecclesiae Hiberniae: The Succession of the Prelates and Members of the Cathedral Bodies of Ireland. Vol. 4. Dublin: Hodges and Smith.
Fryde, E. B.; Greenway, D. E.; Porter, S.; Roy, I., eds. (1986). Handbook of British Chronology (3rd, reprinted 2003 ed.). Cambridge: Cambridge University Press. ISBN0-521-56350-X.
Moody, T. W.; Martin, F. X.; Byrne, F. J., eds. (1984). Maps, Genealogies, Lists: A Companion to Irish History, Part II. A New History of Ireland. Vol. IX. Oxford: Oxford University Press. ISBN0-19-821745-5.