Language & meaning
Meaning & Irish forms
Gaelic Gaelic Irish: a Munster family of the Eóganacht, the same stock as the MacCarthys and O'Callaghans.[1][2]
The name is built on the personal name Súilleabhán, usually explained as “black-eyed”. Woulfe analyses it as Súil-dubhán, from súil, 'eye'. Other sources consulted do not discuss the meaning, so treat this as Woulfe's explanation rather than settled fact.[1]
Place
Where the O'Sullivans 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.
Share of each county's census population. 1926 covers the 26 counties of the Irish Free State only.
Highest concentration · 1901
Kerry
800 per 10,000
13,254 O'Sullivans · 9.43× the national share
Highest share, 1901
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
Highest concentration · 1911
Kerry
763 per 10,000
12,201 O'Sullivans · 9.27× the national share
Highest share, 1911
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
Highest concentration · 1926
Kerry
720 per 10,000
10,736 O'Sullivans · 6.25× the national share
Highest share, 1926
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
County figures as a table
| County | 1901 | 1911 | 1926 | Per 10k 1901 | Per 10k 1911 | Per 10k 1926 |
|---|---|---|---|---|---|---|
| Antrim | 164 | 166 | — | 4 | 4 | — |
| Armagh | 61 | 64 | — | 5 | 5 | — |
| Carlow | 62 | 81 | 85 | 17 | 22 | 25 |
| Cavan | 127 | 140 | 105 | 13 | 15 | 13 |
| Clare | 716 | 684 | 560 | 64 | 66 | 59 |
| Cork | 16,438 | 15,797 | 15,201 | 410 | 402 | 417 |
| Donegal | 34 | 38 | 65 | 2 | 2 | 4 |
| Down | 98 | 92 | — | 3 | 3 | — |
| Dublin | 927 | 1,092 | 1,468 | 21 | 23 | 29 |
| Fermanagh | 14 | 11 | — | 2 | 2 | — |
| Galway | 684 | 735 | 633 | 36 | 40 | 37 |
| Kerry | 13,254 | 12,201 | 10,736 | 800 | 763 | 720 |
| Kildare | 129 | 128 | 166 | 21 | 19 | 29 |
| Kilkenny | 209 | 215 | 275 | 28 | 29 | 39 |
| Laois | 57 | 75 | 96 | 10 | 14 | 19 |
| Leitrim | 25 | 29 | 35 | 4 | 5 | 6 |
| Limerick | 1,926 | 1,937 | 1,926 | 131 | 135 | 138 |
| Londonderry | 17 | 20 | — | 1 | 1 | — |
| Longford | 54 | 61 | 80 | 12 | 14 | 20 |
| Louth | 81 | 115 | 136 | 12 | 18 | 22 |
| Mayo | 176 | 144 | 145 | 9 | 8 | 8 |
| Meath | 98 | 101 | 77 | 14 | 16 | 12 |
| Monaghan | 45 | 40 | 36 | 6 | 6 | 6 |
| Offaly | 124 | 107 | 131 | 21 | 19 | 25 |
| Roscommon | 34 | 28 | 23 | 3 | 3 | 3 |
| Sligo | 6 | 19 | 16 | 1 | 2 | 2 |
| Tipperary | 872 | 821 | 856 | 55 | 54 | 61 |
| Tyrone | 14 | 22 | — | 1 | 2 | — |
| Waterford | 639 | 664 | 697 | 73 | 81 | 89 |
| Westmeath | 96 | 122 | 126 | 16 | 20 | 22 |
| Wexford | 311 | 312 | 301 | 30 | 31 | 32 |
| Wicklow | 83 | 101 | 163 | 14 | 17 | 29 |
Local strongholds in 1911
District Electoral Divisions (300+ residents) where O'Sullivans made up the largest share of the population. In Ardigole, Co. Cork, about one resident in 2 was a O'Sullivan.
| DED | County | O'Sullivans | Share |
|---|---|---|---|
| Ardigole | Cork | 661 | 46.9% |
| Kilcaskan | Cork | 555 | 37.9% |
| Glanmore | Kerry | 276 | 34.9% |
| Ardea | Kerry | 260 | 33.9% |
| Curryglass | Cork | 292 | 31.9% |
| Kilnamanagh | Cork | 437 | 31.8% |
| Dawros | Kerry | 208 | 31.4% |
| Canuig | Kerry | 189 | 30.0% |
Origins
Septs & territories
Many Irish surnames were adopted independently by unrelated families. These are the distinct O'Sullivan lineages described in the sources.
A surname can point you towards a place. On its own, it cannot establish a pedigree.
O'Sullivan Mór
barony of Dunkerron, on Kenmare Bay · Kerry
The senior branch, whose head held the barony of Dunkerron and lived at Dunkerron Castle near Kenmare. O'Hart says the family lost its lands in the Cromwellian confiscations and that the direct line of chiefs ended with the death of Donal O'Sullivan Mór in 1754.[1][6][7]
O'Sullivan Beare
Beare, now the baronies of Beare and Bantry · Cork, Kerry
Lords of the Beara peninsula, with their chief fortress at Dunboy near Castletownbere. Their last chief, Donal Cam, held out after the defeat at Kinsale and led the famous march north in the winter of 1602–03.[1][2][8]
O'Sullivan Maol
0Named by Woulfe as one of the heads of the O'Sullivan branches. He gives no further detail.[1]
Mac Fineen Duff (Mac Finghin Dubh)
0A branch named by Woulfe; Wikipedia describes it as a cadet line of O'Sullivan Beare that is now thought to be extinct.[1][2]
McGillycuddy of the Reeks
around MacGillycuddy's Reeks · Kerry
Wikipedia describes the McGillycuddys as a branch of the O'Sullivans who took the surname Mac Giolla Mochuda around 1600. Their head still uses the title The McGillycuddy of the Reeks.[9][2]
Ó Súileacháin
Longford, Cavan, Louth
An unrelated family whose name, 'descendant of Súileachán' (quick-eyed), was properly Sullahan or Sullehan. Woulfe says it had been almost everywhere wrongly turned into Sullivan, so some Sullivans of the north midlands have this origin.[5]
The name over time
History
Eóganacht roots in Tipperary
The O'Sullivans were part of the Eóganacht, the dynasties that ruled Munster from Cashel, and Woulfe notes they shared descent with the MacCarthys and O'Callaghans. Traditional genealogy traces them to Fíngen mac Áedo Duib, king of Munster, who died in 618. Their original lands lay along the River Suir in south Tipperary, and their main seat was at Knockgraffon, a short distance north of Cahir. Wikipedia notes a claim that Knockgraffon may once have been an inauguration site of the Munster kings, though it treats this as unproven.[1][2][10]
The move west
The Anglo-Norman advance into Munster forced the O'Sullivans out of Tipperary. Woulfe dates their departure to 1192, the year in which, according to Wikipedia, the English of Leinster raised a motte at Knockgraffon during a raid against Donal Mór, chief of the O'Sullivans; the Wikipedia article on the family gives 1193. They resettled on the mountainous coast around Kenmare Bay and Bantry Bay, in what is now south Kerry and west Cork. There, Woulfe says, they built up large estates and rose to be among the strongest families of the province.[1][10][2]
Branches of the family
In their new territory the O'Sullivans divided into several branches, each with its own head. O'Sullivan Mór held the barony of Dunkerron, with a castle near Kenmare. O'Sullivan Beare ruled the Beara peninsula and Bantry. Woulfe also names O'Sullivan Maol and Mac Fineen Duff, and Wikipedia adds the McGillycuddys of the Reeks as an offshoot of O'Sullivan Mór. Alongside the MacCarthys and O'Donoghues they resisted Norman expansion, and Wikipedia records a victory over the Normans in 1261.[1][2][9]
Dunboy and the long march
Donal Cam O'Sullivan Beare joined the Irish and Spanish side in the Nine Years' War. After the defeat at Kinsale at the end of 1601, English forces besieged his fortress at Dunboy in June 1602, destroyed it and hanged the garrison; non-combatants sheltering on Dursey Island were massacred. On 31 December 1602 Donal Cam set out north with about a thousand followers. They reached O'Rourke's castle in Leitrim on 14 January 1603, by which time only 35 remained. He went into exile in Spain and was killed in Madrid in 1618.[8][2]
Exile, learning and poetry
The O'Sullivan estates were confiscated in the 17th century, and O'Hart records the dispossession of O'Sullivan Mór under Cromwell. Many of the family went abroad. Donal Cam's nephew Philip O'Sullivan Beare, born on Dursey, served in the Spanish army and published a history of Catholic Ireland in Spain in 1621. Woulfe quotes O'Callaghan's account of O'Sullivans holding titles in Spain, Belgium and Germany and serving in France's Irish regiments. At home, the name was carried by Munster poets writing in Irish, among them Tadhg Gaelach and Eoghan Rua Ó Súilleabháin.[1][7][11][12][13]
Places linked to the name
- Knockgraffon (Cnoc Rafann), Co. Tipperary — Original seat of the O'Sullivans, north of Cahir, before the Normans drove them west.[1][10]
- Dunkerron Castle, Co. Kerry — Seat of O'Sullivan Mór, near Kenmare.[1][6]
- Dunboy Castle, Co. Cork — Chief fortress of O'Sullivan Beare near Castletownbere, destroyed in the siege of 1602.[14][8]
- Beara Peninsula (Béarra), Co. Cork — Territory of O'Sullivan Beare, now the baronies of Beare and Bantry.[1]
- Dursey Island, Co. Cork — Where O'Sullivan non-combatants were massacred in 1602.[2]
Everyday lives
The O'Sullivans in the census
Who the O'Sullivans were in the 1901 and 1911 censuses (and 1926 where recorded), set against everyone in Ireland in the same census.
O'Sullivans All of Ireland Ireland's figure marked on the O'Sullivan bar
Religion, 1911
Irish language
609 O'Sullivans spoke Irish only in 1901.
Reading & writing
Family life, 1911
Commonest occupations
Adults aged 15+, 1901 and 1911 combined.
| Farmer | 6,737 |
| Farmer's son | 3,503 |
| Farmer's daughter | 1,968 |
| Agricultural labourer | 1,405 |
| Farm servant | 1,354 |
| General labourer | 1,182 |
| Labourer | 1,069 |
| Domestic servant | 811 |
| Farm labourer | 743 |
| House keeper | 728 |
Born outside Ireland
1.0% of O'Sullivans in 1911 gave a birthplace outside Ireland.
| United States | 156 |
| England | 136 |
| Scotland | 26 |
| Wales | 14 |
| India | 12 |
| Australia & NZ | 6 |
Median age: 22 in 1901, 24 in 1911.
Given names
First names among the O'Sullivans
Men and boys
- John8,634
- Patrick5,704
- Michael5,401
- James3,515
- Daniel3,367
- Timothy2,731
- Denis2,329
- Jeremiah2,221
- Thomas1,939
- William1,391
Women and girls
- Mary9,945
- Margaret3,552
- Ellen3,429
- Bridget3,419
- Julia2,522
- Kate2,165
- Hannah1,822
- Catherine1,757
- Nora1,467
- Johanna1,182
All three censuses combined. Top five in 1926: John, Patrick, Michael, James, Daniel; Mary, Margaret, Bridget, Ellen, Julia.
Spellings
Spellings
This page combines the spellings below, which census enumerators and families used for the same name.
| Spelling | 1901 | 1911 | 1926 | Records |
|---|---|---|---|---|
| Sullivan | 30,194 | 26,939 | 19,595 | Search |
| O'Sullivan | 7,381 | 9,223 | 14,543 | Search |
Related forms
- Sullivan — The same name with the O' dropped, a form especially common in North America.[1][15]
- Sullevan, Soolivan — Older anglicised spellings recorded by Woulfe.[1]
- McGillycuddy — The surname adopted by an O'Sullivan branch in Kerry around 1600.[9]
- Sullahan, Sullehan — Proper anglicisations of the unrelated Ó Súileacháin, which was often replaced by Sullivan.[5]
Diaspora
The O'Sullivans abroad
Emigration carried the name worldwide. In the 2010 United States census:
| Spelling | People | US rank |
|---|---|---|
| Sullivan | 220,990 | 105th |
| O'Sullivan | 11,818 | 3032nd |
Source: US Census Bureau, 2010 surname file (public domain).
Heraldry
Is there a O'Sullivan coat of arms?
There is no single O'Sullivan coat of arms for everyone of the name. O'Hart records arms for O'Sullivan Mór, Lords of Dunkerron: a right hand cut off at the wrist, grasping an upright sword, with a crest of a robin holding a sprig of laurel on a ducal coronet, and the motto 'Lamh foistenach abu'. These belonged to the chiefly line of O'Sullivan Mór. Arms are hereditary in a particular family, so sharing the surname does not by itself entitle anyone to them.[7]
Websites selling a single “O'Sullivan 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'Sullivan
- Donal Cam O'Sullivan Beare (1560–1618) Last chief of O'Sullivan Beare, leader of the 1602–03 march from Beara to Leitrim.
- Philip O'Sullivan Beare (c. 1590–c. 1636) Soldier in Spanish service and historian, author of Historiae Catholicae Iberniae (1621).
- Tadhg Gaelach Ó Súilleabháin (c. 1715–1795) Munster poet known for religious verse in Irish.
- Eoghan Rua Ó Súilleabháin (1748–1784) Irish-language poet, one of the last great Gaelic poets of Munster.
- Timothy Daniel Sullivan (1827–1914) Nationalist journalist, MP and poet who wrote the anthem 'God Save Ireland'.
- Arthur Sullivan (1842–1900) English composer of the Gilbert and Sullivan comic operas.
- John L. Sullivan (1858–1918) American boxer, first heavyweight champion of gloved boxing.
- Anne Sullivan (1866–1936) American teacher and lifelong companion of Helen Keller.
- Muiris Ó Súilleabháin (1904–1950) Blasket Islander whose Irish-language memoir is known in English as Twenty Years A-Growing.
- Maureen O'Sullivan (1911–1998) Irish and American actress, Jane in the Johnny Weissmuller Tarzan films.
- Sonia O'Sullivan (born 1969) Irish athlete, 1995 world 5000 metres champion and Olympic silver medallist.
- Ronnie O'Sullivan (born 1975) English snooker player, seven-time world champion.
Questions
Questions about the O'Sullivan name
Is O'Sullivan an Irish surname?
Yes. O'Sullivan is the English form of Ó Súilleabháin, the name of a Gaelic Munster family descended from the Eóganacht kings of Cashel. After the Normans pushed them out of Tipperary around 1192, they settled on the coasts of south Kerry and west Cork, around Kenmare and Bantry bays, and became one of the leading families of Munster.[1][2]
Are Sullivan and O'Sullivan the same name?
Yes, in almost all cases. Woulfe lists both Sullivan and O'Sullivan as English forms of Ó Súilleabháin, and Wikipedia describes Sullivan as the anglicised form with the O' dropped, most common in North America. One exception: Woulfe notes that an unrelated midlands name, Ó Súileacháin, was often anglicised Sullivan too, in Longford, Cavan and Louth.[1][5][15]
What is O'Sullivan in Irish?
Ó Súilleabháin, meaning 'descendant of Súilleabhán'. Woulfe, in 1923, preferred the spelling Ó Súileabháin with a single l and called the double-l form less correct, but Ó Súilleabháin is the form used in the modern standard and in the Gaois surname database. Both spellings appear in older books and records, so it is worth searching under each.[1][3][4]
How do you pronounce O'Sullivan?
In English, oh-SULL-iv-un, with the stress on the second syllable. In Irish, Ó Súilleabháin varies by dialect. Wiktionary gives a pronunciation roughly like 'oh SOOL-uh-vawn' in Munster, where most of the family lived, 'oh SOOL-uh-wawn' in Connacht, and 'uh SOOL-a-wawn' in Ulster, where the Ó is reduced to a light vowel.[4]
What does O'Sullivan mean?
It means 'descendant of Súilleabhán'. Woulfe explains the personal name as Súil-dubhán, 'black-eyed', built on súil, 'eye'. That is the explanation given in the standard 1923 dictionary of Irish surnames. The other sources we consulted for this page do not discuss the meaning, so we present it as Woulfe's view rather than as settled fact.[1]
Is there an O'Sullivan family crest or coat of arms?
Not one for everyone of the name. O'Hart records arms for O'Sullivan Mór, Lords of Dunkerron: a hand grasping an upright sword, a robin crest, and the motto 'Lamh foistenach abu'. These belonged to the chief's line, not to the whole name. Anyone wanting to use arms legitimately would need to show descent from that line.[7]
Where in Ireland is the O'Sullivan surname most common?
In the 1911 census the largest numbers of O'Sullivans lived in Cork (15,797), Kerry (12,201), Limerick (1,937). Relative to population, the name was most concentrated in Kerry (763 per 10,000), Cork (402 per 10,000), Limerick (135 per 10,000).
How common was the O'Sullivan surname in Ireland?
36,162 people were recorded as Sullivan or O'Sullivan in the 1911 census of Ireland, making it the 4th most common surname. That is roughly 0.8% of the population, or 1 person in 121.
Looking for a O'Sullivan ancestor?
Search every O'Sullivan household in the 1901, 1911 and 1926 censuses, with free images of the original forms.
Evidence
Sources
- Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Ó Súileabháin' (1923)
- Wikipedia contributors, O'Sullivan family (2026)
- Gaois research group, Dublin City University, Sloinnte: Irish surname dataset (version 2) (2022). Modern standard Irish forms.
- Wiktionary contributors, Ó Súilleabháin (2026)
- Patrick Woulfe, Sloinnte Gaedheal is Gall: Irish Names and Surnames, entry 'Ó Súileacháin' (1923)
- Wikipedia contributors, Dunkerron Castle (2026)
- John O'Hart, Irish Pedigrees, 'O'Sullivan Mór (No.2): Lords of Dunkerron' (1892)
- Wikipedia contributors, Donal Cam O'Sullivan Beare (2026)
- Wikipedia contributors, McGillycuddy of the Reeks (2026)
- Wikipedia contributors, Knockgraffon (2026)
- Wikipedia contributors, Philip O'Sullivan Beare (2026)
- Wikipedia contributors, Eoghan Rua Ó Súilleabháin (2026)
- Wikipedia contributors, Tadhg Gaelach Ó Súilleabháin (2026)
- Wikipedia contributors, Dunboy Castle (2026)
- Wikipedia contributors, Sullivan (surname) (2026)
- 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.