surnames.ie

Irish surname · 5th most common in 1911

O'Connor

Also spelt Connor, Connors, OConner, OConnors

O'Connor comes from the Irish Ó Conchobhair, 'descendant of Conchobhar', an old personal name. At least six unrelated families bore it, most famously the O'Conor kings of Connacht, but also lords in Offaly, north Kerry, west Clare and County Derry. Connor and Connors are the same name without the O.

Irish Ó Conchobhair · Ó ConchúirIrish Mac Conchobhair
1901 census
33,848
#5 · 76 per 10,000
1911 census
33,346
#5 · 76 per 10,000
1926 census
30,749
#5 · 104 per 10,000
Most numerous
Kerry
Highest share: Kerry

Language & meaning

Meaning & Irish forms

Gaelic Gaelic Irish: at least six distinct families, each descended from a different Conchobhar, in Connacht, Offaly, Kerry, Clare, Derry and Oriel.[1]

Ó Conchobhair
Modern spelling: Ó Conchúir
“descendant of Conchobhar”[1][2]
Woulfe also gives the spelling Ó Conchubhair. Older English renderings include O Conchor and O Connour.
Mac Conchobhair
“son of Conchobhar”[3]
A separate surname with many anglicised forms, such as MacNogher and Noher, and sometimes simply Connor.

The name is built on the personal name Conchobhar, usually explained as “high-will or desire”. Woulfe's gloss. He describes it as an ancient and very common Irish personal name, rendered in Latin as Cornelius, which is why Cornelius was once used as its English equivalent.[1][3]

Pronunciation

O'Connor: oh-KON-er

Place

Where the O'Connors lived

How common the name was in each county, as a share of the population, in the three surviving full censuses of Ireland. Use the buttons to compare years.

Donegal: 15.3 per 10,000 (258 people) Waterford: 77.5 per 10,000 (638 people) Dublin: 71.6 per 10,000 (3,440 people) Kilkenny: 29.2 per 10,000 (219 people) Carlow: 58.1 per 10,000 (211 people) Limerick: 165.1 per 10,000 (2,367 people) Louth: 60.8 per 10,000 (383 people) Tipperary: 81.6 per 10,000 (1,246 people) Roscommon: 110.5 per 10,000 (1,038 people) Meath: 50.6 per 10,000 (330 people) Wicklow: 54.9 per 10,000 (334 people) Cavan: 16.8 per 10,000 (153 people) Cork: 111.4 per 10,000 (4,378 people) Clare: 103.5 per 10,000 (1,081 people) Galway: 85.4 per 10,000 (1,557 people) Mayo: 56.8 per 10,000 (1,092 people) Sligo: 89.3 per 10,000 (707 people) Leitrim: 26.8 per 10,000 (169 people) Offaly: 95.7 per 10,000 (545 people) Laois: 64.3 per 10,000 (352 people) Kildare: 67.9 per 10,000 (454 people) Kerry: 478.9 per 10,000 (7,655 people) Monaghan: 28.7 per 10,000 (205 people) Wexford: 142.7 per 10,000 (1,461 people) Longford: 58.6 per 10,000 (257 people) Westmeath: 59.6 per 10,000 (359 people) Tyrone: 12.3 per 10,000 (176 people) Antrim: 22.4 per 10,000 (1,071 people) Armagh: 11.8 per 10,000 (141 people) Fermanagh: 22.4 per 10,000 (136 people) Londonderry: 43.5 per 10,000 (608 people) Down: 10.6 per 10,000 (325 people)
fewerup to 485 per 10,000

Share of each county's census population. 1926 covers the 26 counties of the Irish Free State only.

Highest concentration · 1911

Kerry

479 per 10,000

7,655 O'Connors · 6.31× the national share

Highest share, 1911

  1. Kerry 479
  2. Limerick 165
  3. Wexford 143
  4. Cork 111
  5. Roscommon 111
  6. Clare 104
  7. Offaly 96
  8. Sligo 89

Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.

County figures as a table
County190119111926Per 10k 1901Per 10k 1911Per 10k 1926
Antrim9741,071—2122—
Armagh152141—1212—
Carlow171211246465872
Cavan163153139171717
Clare1,1731,08191010410496
Cork4,4084,3784,474110111123
Donegal194258305111520
Down367325—1311—
Dublin3,0673,4403,930707279
Fermanagh143136—2222—
Galway1,6671,5571,449878586
Kerry8,0417,6557,208485479484
Kildare451454493746885
Kilkenny213219184282926
Laois400352349706468
Leitrim187169162272729
Limerick2,2942,3672,452156165176
Londonderry679608—4744—
Longford267257274575969
Louth376383431586169
Mayo1,1991,0921,033615760
Meath401330348575156
Monaghan282205331382951
Offaly5535455349296102
Roscommon1,0711,038935107111112
Sligo707707642888990
Tipperary1,2321,2461,181778284
Tyrone166176—1112—
Waterford616638701707890
Westmeath349359360566064
Wexford1,5281,4611,365147143144
Wicklow357334313605555

Local strongholds in 1911

District Electoral Divisions (300+ residents) where O'Connors made up the largest share of the population. In Doonasleen, Co. Cork, about one resident in 6 was a O'Connor.

DEDCountyO'ConnorsShare
DoonasleenCork138 16.0%
CaherLimerick95 15.3%
LackabawnKerry110 15.2%
KnocknagashelKerry202 12.8%
BrosnaKerry172 12.7%
CloghaneKerry87 12.5%
DerrianaKerry88 12.3%
LickeenKerry45 11.5%

Origins

Septs & territories

Many Irish surnames were adopted independently by unrelated families. These are the distinct O'Connor lineages described in the sources.

A surname can point you towards a place. On its own, it cannot establish a pedigree.

Ó Conchobhair of Connacht (O'Conor)

Connacht, especially Roscommon · Roscommon, Sligo

The royal family of Connacht, named after Conchobhar, a king of Connacht in the late 10th century according to Woulfe. Two of them, Turlough Mór and Rory, were High Kings of Ireland. The family later split into O'Conor Don, O'Conor Roe and O'Conor Sligo; the head of the family is still styled The O'Conor Don and its seat is Clonalis House near Castlerea.[1][4][5][6]

Ó Conchobhair Failghe (O'Connor Faly)

Uí Failge (Offaly) · Offaly, Kildare, Laois

Rulers of Uí Failge, whose surname comes from an Offaly lord named Conchobhar mac Fionn (d. 979). Woulfe says they resisted the English of the Pale for more than three centuries from their stronghold at Dangan, later Philipstown. They lost their lands in the plantation of the 1550s under Philip and Mary. Wikipedia stresses they were unrelated to the Connacht and Kerry O'Connors.[1][7]

Ó Conchobhair Chiarraí (O'Connor Kerry)

north Kerry; later the barony of Iraghticonnor · Kerry

Before the Anglo-Norman invasion their chief ruled Kerry between Tralee and the Shannon. Pressure from the Fitzmaurices and other settlers reduced them to the barony of Iraghticonnor, which they held until the end of Elizabeth I's reign. Their chief stronghold was Carrigafoyle Castle near Ballylongford.[1][8][9]

Ó Conchobhair of Corcomroe

barony of Corcomroe · Clare

Named after Conchobhar, son of Maelseachlainn, lord of Corcomroe, who was killed in 1002. Their chiefs ruled the west Clare barony of Corcomroe into the late 1500s.[1]

Ó Conchobhair of Keenaght

Cianachta, now the barony of Keenaght · Derry

Lords of Cianachta in County Derry until the O'Kanes displaced them shortly before the Anglo-Norman invasion. O'Hart records the same tradition.[1][10]

Ó Conchobhair of Uí Breasail

Uí Breasail

A family of Uí Breasail, a branch of the Oirghialla. Woulfe names them but gives no further detail.[1]

Ó hOireachtaigh of Abbeyfeale

around Abbeyfeale · Limerick

Woulfe records that almost all members of this unrelated family near Abbeyfeale had taken the surname O'Connor 'for a peculiar local reason', which he does not explain. Elsewhere their name became Heraghty, Harty or Geraghty.[11]

The name over time

History

Six families, one personal name

Conchobhar was among the most popular names in early Ireland, and families descended from different men of that name each became Ó Conchobhair. Woulfe counts at least six distinct families: in Connacht, Offaly, Kerry, Corcomroe in Clare, Keenaght in Derry, and Uí Breasail in Oriel. They had different ancestors, territories and histories. Wikipedia makes the same point about the Offaly family, describing it as unrelated to the O'Connors of Connacht and Kerry. A shared surname is no evidence of a shared origin.[1][7]

Kings of Connacht

The Connacht O'Conors belonged to the Síol Muireadaigh and ruled the province on and off from the 10th century, and without a break from 1102 to 1475, according to Wikipedia. Sources differ over which Conchobhar gave them their name: Woulfe points to a king of the late 10th century, while Wikipedia dates the founder to 872. Their high point came with Turlough Mór Ó Conchobhair, king of Connacht from 1106 to 1156 and High King, and his son Rory, the last High King before the Anglo-Norman invasion.[1][5][12][13]

O'Conor Don, Roe and Sligo

Because chiefs were chosen from a wide kin group rather than by strict primogeniture, the Connacht family split into rival lines. Woulfe names three: O'Conor Donn (the brown), O'Conor Ruadh (the red) and O'Conor Sligo. The Sligo line descended from Brian Luighnech, a son of Turlough Mór, and held lordship in Sligo into the 17th century. The O'Conor Don line survived longest. Charles O'Conor of Belanagare, the 18th-century antiquarian, came from this family, and in 1820 Owen O'Conor inherited the title and moved to Clonalis House near Castlerea, still the family seat.[1][4][5][14][6]

O'Connor Faly and the Pale

The O'Connors of Offaly were the ruling family of Uí Failge, a kingdom covering east Offaly and parts of Kildare and Laois. Their surname commemorates an Offaly lord, Conchobhar mac Fionn, who died in 979. Woulfe describes them as a warlike family who held off the English of the Pale for over three hundred years, with their chief stronghold at Dangan. They lost their lands under Philip and Mary, when an act of 1556 divided their territory among King's County, Queen's County and Kildare, and Dangan was renamed Philipstown after Philip II. The town is now Daingean.[1][7][15]

O'Connor Kerry and Carrigafoyle

In north Kerry, the O'Connors were once lords of all the land between Tralee and the Shannon. Anglo-Norman settlers, the Fitzmaurices in particular, steadily reduced them to the barony that still bears their name, Iraghticonnor, from Oireacht Uí Chonchúir, 'the inheritance of the O'Connors'. Around the 1490s Conor Liath O'Connor Kerry built Carrigafoyle Castle on the Shannon estuary. During the Desmond rebellion it was besieged and stormed by English forces at Easter 1580. Woulfe records that the family's lands were confiscated at the end of Elizabeth's reign and given to Trinity College Dublin.[1][8][9]

Clare, Derry and other O'Connors

Two smaller lordships complete the picture. The O'Connors of Corcomroe took their name from Conchobhar, lord of Corcomroe, killed in 1002, and ruled that barony in west Clare until the end of the 16th century. The O'Connors of Keenaght in County Derry lost their lordship to the O'Kanes before the Normans arrived. Some O'Connors have a different origin again: Woulfe notes that a family named Ó hOireachtaigh around Abbeyfeale had almost all become O'Connor, and that the separate name Mac Conchobhair was sometimes anglicised simply as Connor.[1][11][3]

Places linked to the name

  • Clonalis House, Co. Roscommon — Seat of The O'Conor Don, near Castlerea.[5][6]
  • Daingean (Philipstown) (An Daingean), Co. Offaly — Chief stronghold of O'Connor Faly, renamed Philipstown after the plantation.[1][15]
  • Iraghticonnor (Oireacht Uí Chonchúir), Co. Kerry — Barony named after the O'Connors of Kerry, 'the inheritance of the O'Connors'.[1][8]
  • Carrigafoyle Castle, Co. Kerry — O'Connor Kerry stronghold near Ballylongford, besieged in 1580.[1][9]
  • Corcomroe, Co. Clare — Barony ruled by an O'Connor family until the end of the 16th century.[1]
  • Keenaght (Cianachta), Co. Derry — Barony once ruled by an O'Connor family, displaced by the O'Kanes.[1]

Everyday lives

The O'Connors in the census

Who the O'Connors were in the 1901 and 1911 censuses (and 1926 where recorded), set against everyone in Ireland in the same census.

O'Connors All of Ireland Ireland's figure marked on the O'Connor bar

Religion, 1911

Catholic +22.5 points vs Ireland
O'Connors 96.1%
All of Ireland 73.6%
Church of Ireland −10.7 points vs Ireland
O'Connors 2.5%
All of Ireland 13.2%
Presbyterian −9.1 points vs Ireland
O'Connors 1.0%
All of Ireland 10.1%
Methodist & other −2.7 points vs Ireland
O'Connors 0.4%
All of Ireland 3.1%

Irish language

Spoke Irish, 1901 +10.1 points vs Ireland
O'Connors 25.4%
All of Ireland 15.3%
Spoke Irish, 1911 +8.1 points vs Ireland
O'Connors 21.6%
All of Ireland 13.5%
Spoke Irish, 1926 · 26 counties +2.8 points vs Ireland
O'Connors 16.3%
All of Ireland 13.5%

319 O'Connors spoke Irish only in 1901.

Reading & writing

Could read and write, 1901 · aged 15+ −0.9 points vs Ireland
O'Connors 79.5%
All of Ireland 80.4%
Could read and write, 1911 · aged 15+ −0.9 points vs Ireland
O'Connors 84.9%
All of Ireland 85.8%

Family life, 1911

Household size · 6,737 households about the same as Ireland
O'Connors 4.88
All of Ireland 4.83
Children born per mother · women 45–59 higher than Ireland
O'Connors 6.88
All of Ireland 6.46
Children still living about the same as Ireland
O'Connors 79.9%
All of Ireland 79.8%

Commonest occupations

Adults aged 15+, 1901 and 1911 combined.

Farmer5,981
Farmer's son3,105
Farmer's daughter1,686
Agricultural labourer1,276
General labourer1,164
Farm servant1,161
Labourer949
House keeper712
Farm labourer673
Domestic servant644

Born outside Ireland

1.6% of O'Connors in 1911 gave a birthplace outside Ireland.

England307
United States95
Scotland83
India19
Australia & NZ5
Canada2

Median age: 23 in 1901, 25 in 1911.

Given names

First names among the O'Connors

Men and boys

  1. John7,602
  2. Patrick5,654
  3. Michael4,422
  4. James3,891
  5. Thomas3,804
  6. William1,831
  7. Daniel1,338
  8. Timothy1,170
  9. Denis1,048
  10. Jeremiah927

Women and girls

  1. Mary8,636
  2. Bridget3,785
  3. Margaret2,993
  4. Ellen2,587
  5. Catherine1,926
  6. Kate1,733
  7. Annie1,460
  8. Julia1,188
  9. Elizabeth1,008
  10. Hannah974

All three censuses combined. Top five in 1926: John, Patrick, Michael, Thomas, James; Mary, Bridget, Margaret, Ellen, Annie.

Spellings

Spellings

This page combines the spellings below, which census enumerators and families used for the same name.

Spelling190119111926Records
O'Connor14,61516,97221,107Search
Connor14,62712,3897,219Search
Connors4,2513,6832,306Search
OConner16318061Search
OConnors19212256Search

Related forms

  • O'Conor — The spelling used by the Connacht royal family, including The O'Conor Don.[1][4][5]
  • Connor — The same name without the O'. It can also represent Mac Conchobhair.[1][3]
  • Connors — An anglicised form of Ó Conchobhair recorded by Woulfe.[1][2]
  • MacNogher, Noher, Naughter — Forms of the separate surname Mac Conchobhair.[3]

Diaspora

The O'Connors abroad

Emigration carried the name worldwide. In the 2010 United States census:

SpellingPeopleUS rank
O'Connor77,923417th
Connor29,3461207th
Connors19,6371823rd
OConner3,6119048th
OConnors173103655th

Source: US Census Bureau, 2010 surname file (public domain).

Heraldry

Is there a O'Connor coat of arms?

There is no single O'Connor coat of arms, because the name belongs to several unrelated families. O'Hart records different arms for different lines: an oak tree with a crown for O'Conor Don; a crowned gold lion on green, with the motto 'Nec timeo, nec sperno', for the O'Connors of Kerry; and an oak tree on a mount for the O'Connors of Keenaght. Each belongs to its own family line.[16][17][10]

Websites selling a single “O'Connor family crest” are selling a design, not an inheritance. Arms in Ireland belonged to individuals and their heirs, and the Chief Herald of Ireland still grants arms that way today.

People

Notable people named O'Connor

  • Turlough Mór O'Conor (1088–1156)
    King of Connacht from 1106 and High King of Ireland.
  • Rory O'Conor (c. 1116–1198)
    King of Connacht and the last High King of Ireland before the Anglo-Norman invasion.
  • Charles O'Conor of Belanagare (1710–1791)
    Roscommon antiquarian and historian, an influential advocate for preserving Irish culture.
  • Arthur O'Connor (1763–1852)
    United Irishman, arrested on the eve of 1798, later a general in Napoleon's army.
  • Feargus O'Connor (1796–1855)
    Irish Chartist leader and MP, publisher of the Northern Star newspaper.
  • T. P. O'Connor (1848–1929)
    Irish nationalist journalist and MP for nearly fifty years.
  • Roderic O'Conor (1860–1940)
    Roscommon-born painter who worked in France with the Pont-Aven group.
  • Rory O'Connor (1883–1922)
    IRA Director of Engineering; chaired the anti-Treaty IRA's military council in 1922.
  • Christy O'Connor Snr (1924–2016)
    Irish professional golfer, one of the leading players on the British and Irish circuit.
  • Flannery O'Connor (1925–1964)
    American novelist, short-story writer and essayist.
  • Sinéad O'Connor (1966–2023)
    Irish singer, songwriter and activist.
  • Joseph O'Connor (born 1963)
    Irish novelist, author of the international bestseller Star of the Sea.

Questions

Questions about the O'Connor name

Is O'Connor an Irish surname?

Yes. O'Connor is the English form of Ó Conchobhair, 'descendant of Conchobhar'. Woulfe counts at least six separate Gaelic families of the name, including the kings of Connacht, the lords of Offaly, and the O'Connors of north Kerry, west Clare and Derry. Each had its own territory and ancestry.[1]

What is O'Connor in Irish?

The modern standard form is Ó Conchúir, meaning 'descendant of Conchobhar'. Older spellings are Ó Conchobhair and Ó Conchubhair, which is how the name appears in Woulfe's 1923 dictionary and in historical writing about the medieval dynasties. All three refer to the same surname, so it is worth searching under each in older records and Irish-language sources.[2][1]

Is it O'Conor or O'Connor?

Both are correct, and Woulfe lists both as English forms of Ó Conchobhair. The single-n spelling O'Conor is the one used by the royal family of Connacht, whose head is The O'Conor Don. The double-n O'Connor appears in the historical styles O'Connor Faly and O'Connor Kerry. The spelling alone does not tell you which family someone descends from.[1][4][5]

Are Connor, Connors and O'Connor the same name?

Usually, yes. Woulfe lists Connor and Connors among the anglicised forms of Ó Conchobhair, the O' having been dropped as it was from many Irish names. Some Connors, however, come from the separate name Mac Conchobhair, which Woulfe says was also sometimes anglicised Connor.[1][3][2]

Are all O'Connors descended from the kings of Connacht?

No. Only one of the O'Connor families was the royal house of Connacht. The O'Connors of Offaly, Kerry, Corcomroe and Keenaght were separate families named after different men called Conchobhar, and Wikipedia describes the Offaly line as unrelated to those of Connacht and Kerry.[1][7]

Is there an O'Connor family crest or coat of arms?

There are several, because there are several O'Connor families. O'Hart records an oak tree under a crown for O'Conor Don, a crowned lion with the motto 'Nec timeo, nec sperno' for the O'Connors of Kerry, and an oak tree on a mount for the O'Connors of Keenaght. Each belongs to its own line, not to everyone called O'Connor.[16][17][10]

Where in Ireland is the O'Connor surname most common?

In the 1911 census the largest numbers of O'Connors lived in Kerry (7,655), Cork (4,378), Dublin (3,440). Relative to population, the name was most concentrated in Kerry (479 per 10,000), Limerick (165 per 10,000), Wexford (143 per 10,000).

How common was the O'Connor surname in Ireland?

33,346 people were recorded as O'Connor or Connor or Connors or OConner or OConnors in the 1911 census of Ireland, making it the 5th most common surname. That is roughly 0.8% of the population, or 1 person in 132.

Looking for a O'Connor ancestor?

Search every O'Connor household in the 1901, 1911 and 1926 censuses, with free images of the original forms.

Search records on irishcensus.com

Evidence

Sources

  1. Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Ó Conchobhair' (1923)
  2. Gaois research group, Dublin City University, Sloinnte: Irish surname dataset (version 2) (2022). Modern standard Irish forms.
  3. Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Mac Conchobhair' (1923)
  4. Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Ó Conchobhair Donn' (1923)
  5. Wikipedia contributors, O'Conor (2026)
  6. Wikipedia contributors, Clonalis House (2026)
  7. Wikipedia contributors, Uí Failge (2026)
  8. Wikipedia contributors, Iraghticonnor (2026)
  9. Wikipedia contributors, Siege of Carrigafoyle Castle (2026)
  10. John O'Hart, Irish Pedigrees, 'O'Connor: of Keenaght' (1892)
  11. Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Ó hOireachtaigh' (1923)
  12. Wikipedia contributors, Tairrdelbach Ua Conchobair (2026)
  13. Wikipedia contributors, Ruaidrí Ua Conchobair (2026)
  14. Wikipedia contributors, O'Conor Sligo (2026)
  15. Wikipedia contributors, Daingean (2026)
  16. John O'Hart, Irish Pedigrees, 'O'Conor Don (No.3)' (1892)
  17. John O'Hart, Irish Pedigrees, 'O'Connor (No.1): Lords of Kerry' (1892)
  18. Census of Ireland 1901 and 1911, and Census of Population 1926, National Archives of Ireland. Counts compiled by surnames.ie from the irishcensus.com transcription (dataset 20260831130351). 1926 data © National Archives of Ireland, CC BY 4.0.

How we compile these figures: methodology.