surnames.ie

Irish surname · 90th most common in 1911

O'Regan

Also spelt Regan

O'Regan and Regan come from the Irish Ó Riagáin, 'descendant of Riagán'. Two unrelated families bore it: lords of south Brega in Meath, one of the Four Tribes of Tara, and a Dalcassian family of Thomond said to descend from a nephew of Brian Boru. Reagan is a spelling of the same name.

Irish Ó RiagáinIrish Ó RéagáinIrish Ó RéigínIrish Ua Riagáin
1901 census
7,453
#95 · 17 per 10,000
1911 census
7,475
#90 · 17 per 10,000
1926 census
7,276
#69 · 25 per 10,000
Most numerous
Cork
Highest share: Roscommon

Language & meaning

Meaning & Irish forms

Gaelic Gaelic Irish: two distinct families called Ó Riagáin, one of the southern Uí Néill in Meath and one of the Dál gCais in Thomond.[1][2]

Ó Riagáin
“descendant of Riagán”[1][3]
Woulfe's headword and the main Irish form in Gaois, with O'Regan and Regan as its English forms.
Ó Réagáin
“descendant of Riagán”[4][1][3]
Woulfe calls this a common spoken variant of Ó Riagáin; Gaois lists it as an alternative Irish form.
Ó Réigín
“descendant of Riagán”[5]
A further variant of Ó Riagáin recorded by Woulfe, also anglicised O'Regan or Regan.
Ua Riagáin
“grandson or descendant of Riagán”[2][6]
The older spelling, found in the annals, as in the name of Mathghamhain Ua Riagáin, king of Brega.

The name is built on the personal name Riagán, usually explained as “uncertain; possibly linked to rí, 'king'”. Woulfe gives the personal name without a meaning. Wikipedia suggests it may come from rí, 'sovereign' or 'king', with a diminutive ending, but presents this only as likely.[1][2]

Pronunciation

O'Regan: oh-REE-gun

Place

Where the O'Regans 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: 0.5 per 10,000 (8 people) Waterford: 21.6 per 10,000 (178 people) Dublin: 3.7 per 10,000 (179 people) Kilkenny: 4.4 per 10,000 (33 people) Carlow: 3.9 per 10,000 (14 people) Limerick: 26.7 per 10,000 (383 people) Louth: 0.8 per 10,000 (5 people) Tipperary: 6.9 per 10,000 (106 people) Roscommon: 102.7 per 10,000 (965 people) Meath: 12.1 per 10,000 (79 people) Wicklow: 1.3 per 10,000 (8 people) Cavan: 1.5 per 10,000 (14 people) Cork: 84.9 per 10,000 (3,338 people) Clare: 6.3 per 10,000 (66 people) Galway: 14.1 per 10,000 (257 people) Mayo: 35.2 per 10,000 (677 people) Sligo: 24.9 per 10,000 (197 people) Leitrim: 16.5 per 10,000 (104 people) Offaly: 4.4 per 10,000 (25 people) Laois: 0.7 per 10,000 (4 people) Kildare: 6.7 per 10,000 (45 people) Kerry: 27.8 per 10,000 (445 people) Monaghan: 1.5 per 10,000 (11 people) Wexford: 2.1 per 10,000 (22 people) Longford: 9.1 per 10,000 (40 people) Westmeath: 3.3 per 10,000 (20 people) Tyrone: 3.8 per 10,000 (54 people) Antrim: 1.5 per 10,000 (72 people) Armagh: 0.6 per 10,000 (7 people) Fermanagh: 2.1 per 10,000 (13 people) Londonderry: 2.6 per 10,000 (37 people) Down: 2.3 per 10,000 (69 people)
fewerup to 104 per 10,000

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

Highest concentration · 1911

Roscommon

103 per 10,000

965 O'Regans · 6.03× the national share

Highest share, 1911

  1. Roscommon 103
  2. Cork 85
  3. Mayo 35
  4. Kerry 28
  5. Limerick 27
  6. Sligo 25
  7. Waterford 22
  8. Leitrim 17

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
Antrim5972—12—
Armagh97—11—
Carlow121416345
Cavan171421223
Clare856684869
Cork3,3503,3383,319848591
Donegal12814111
Down7169—32—
Dublin142179253345
Fermanagh913—12—
Galway245257274131416
Kerry422445455262831
Kildare324542577
Kilkenny263337345
Laois15418314
Leitrim10010498141717
Limerick376383400262729
Londonderry3337—23—
Longford4440569914
Louth1256211
Mayo651677615333536
Meath977983141213
Monaghan0113021
Offaly182519344
Roscommon1,047965860104103103
Sligo170197194212527
Tipperary107106131779
Tyrone5754—44—
Waterford179178189212224
Westmeath152041237
Wexford382239424
Wicklow389112

Local strongholds in 1911

District Electoral Divisions (300+ residents) where O'Regans made up the largest share of the population. In Ballaghadereen, Co. Roscommon, about one resident in 15 was a O'Regan.

DEDCountyO'RegansShare
BallaghadereenRoscommon281 6.6%
Tumna SouthRoscommon48 6.5%
Cape ClearCork62 6.1%
WallstownCork19 6.0%
RosscarberyCork63 5.5%
SkullCork116 5.4%
ShanballymoreCork35 5.3%
OakportRoscommon18 5.3%

Origins

Septs & territories

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

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

Ó Riagáin of Brega

south Brega in Meath and the north of the present Co. Dublin · Meath, Dublin

A branch of the southern Uí Néill, counted among the Four Tribes of Tara. Until the Anglo-Norman invasion they ruled south Brega and fought prominently against the Norse. Woulfe says they lost their lands soon after the invasion and scattered across Ireland.[1][2][7]

Ó Riagáin of Thomond

Thomond · Clare

A Dalcassian family, traditionally descended from Riagán, son of Donncuan. Donncuan was a son of Cennétig mac Lorcáin and a brother of Brian Boru, and was killed in 950.[1][2][8]

The name over time

History

Two families, one name

O'Regan is the English form of Ó Riagáin, 'descendant of Riagán'. Woulfe and Wikipedia agree that the name was borne by two separate families, one in the old kingdom of Meath and one in Thomond, which they treat as distinct. Wikipedia suggests the personal name Riagán may be built on rí, 'king', with a diminutive ending, though this is offered as likely rather than certain. In everyday Irish speech the name was often said as Ó Réagáin, which helps explain why Regan and Reagan sit alongside O'Regan in English.[1][4][2]

Lords of south Brega

The Meath O'Regans belonged to the southern Uí Néill and were counted among the Four Tribes of Tara, together with the O'Harts, O'Kellys and O'Connollys. Wikipedia describes the princes of Tara as also styled princes of Brega, a territory reaching across parts of modern Meath, Louth and Dublin and taking in Tara, Trim and Navan. Before the Anglo-Norman invasion the O'Regans were lords of south Brega and the north of present-day Co. Dublin, and they were active in the wars against the Norse of Dublin.[1][7][9][2]

The ransom of 1029

The best-recorded O'Regan of this period is Mathghamhain Ua Riagáin, king of Brega. In 1029 he captured Amlaíb, son of Sigtrygg Silkbeard, king of Dublin, and a grandson of Brian Boru through his mother. The annals list a huge ransom for his release: 1,200 cows, 140 British horses, 60 ounces each of gold and silver, the 'sword of Carlus', the Irish hostages of Leinster and Leth Cuinn, and four further hostages to Ua Riagáin as a pledge of peace. Amlaíb was later killed in England in 1034 while travelling on pilgrimage to Rome.[6][1][2]

After the invasion

According to Woulfe, the O'Regans of Brega were driven from their lands soon after the Anglo-Norman invasion and dispersed throughout Ireland, which is one reason the name later became widespread. One Regan stands at the very start of that story. The Song of Dermot and the Earl, an Anglo-Norman verse account of the coming of Strongbow, names Morice Regan as secretary to Diarmait Mac Murchada, king of Leinster, and as an eyewitness who may have supplied the poet's information. The sources do not say which family he belonged to.[1][10]

The Dalcassian O'Regans

The second family belonged to the Dál gCais of Thomond, the dynasty of the O'Briens. Woulfe and Wikipedia both record the tradition that they descend from Riagán, son of Donncuan, Brian Boru's brother. Donncuan was one of the sons of Cennétig mac Lorcáin, king of the Dál gCais, and was killed in 950 while resisting an invasion of Munster by the High King Congalach Cnogba. Woulfe offers no later history for this branch, but notes that by his day O'Regans were numerous throughout Ireland.[1][2][8]

Regan, O'Regan and Reagan

Woulfe lists O'Regan and Regan side by side as English forms of Ó Riagáin, and Gaois treats both as main forms, so the presence or absence of the O says nothing about which family a person belongs to. Reagan is another rendering of the same Irish name. The best-known example began with Michael O'Regan, baptised at Ballyporeen, Co. Tipperary, in 1829. He moved to London, changed the spelling to Reagan, and in 1857 emigrated to Illinois. His great-grandson Ronald Reagan became the 40th President of the United States.[2][11][12][13]

Places linked to the name

  • Brega, Co. Meath — Medieval kingdom north of Dublin; the O'Regans were lords of its southern part before the invasion.[9][1]
  • Hill of Tara, Co. Meath — Royal site within Brega, associated with the Four Tribes of Tara, among them the O'Regans.[7][9]
  • Ballyporeen (Béal Átha Póirín), Co. Tipperary — Home village of Michael O'Regan, great-grandfather of Ronald Reagan, baptised there in 1829.[12]

Everyday lives

The O'Regans in the census

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

O'Regans All of Ireland Ireland's figure marked on the O'Regan bar

Religion, 1911

Catholic +24.7 points vs Ireland
O'Regans 98.3%
All of Ireland 73.6%
Church of Ireland −11.9 points vs Ireland
O'Regans 1.3%
All of Ireland 13.2%
Presbyterian −10.0 points vs Ireland
O'Regans 0.1%
All of Ireland 10.1%
Methodist & other −2.7 points vs Ireland
O'Regans 0.4%
All of Ireland 3.1%

Irish language

Spoke Irish, 1901 +13.1 points vs Ireland
O'Regans 28.4%
All of Ireland 15.3%
Spoke Irish, 1911 +9.2 points vs Ireland
O'Regans 22.7%
All of Ireland 13.5%
Spoke Irish, 1926 · 26 counties +2.0 points vs Ireland
O'Regans 15.5%
All of Ireland 13.5%

32 O'Regans spoke Irish only in 1901.

Reading & writing

Could read and write, 1901 · aged 15+ −2.6 points vs Ireland
O'Regans 77.8%
All of Ireland 80.4%
Could read and write, 1911 · aged 15+ −2.2 points vs Ireland
O'Regans 83.6%
All of Ireland 85.8%

Family life, 1911

Household size · 1,508 households about the same as Ireland
O'Regans 4.82
All of Ireland 4.83
Children born per mother · women 45–59 higher than Ireland
O'Regans 6.73
All of Ireland 6.46
Children still living +1.4 points vs Ireland
O'Regans 81.2%
All of Ireland 79.8%

Commonest occupations

Adults aged 15+, 1901 and 1911 combined.

Farmer1,519
Farmer's son758
Farmer's daughter443
General labourer242
Farm servant237
Agricultural labourer219
Labourer211
House keeper154
Farmer's wife142
Farm labourer132

Born outside Ireland

0.8% of O'Regans in 1911 gave a birthplace outside Ireland.

England33
United States15
Scotland6
Australia & NZ5
India1
Wales1

Median age: 23 in 1901, 24 in 1911.

Given names

First names among the O'Regans

Men and boys

  1. John1,739
  2. Patrick1,275
  3. Michael1,195
  4. Thomas740
  5. James688
  6. William429
  7. Daniel423
  8. Timothy370
  9. Denis368
  10. Jeremiah293

Women and girls

  1. Mary1,888
  2. Bridget811
  3. Ellen719
  4. Margaret700
  5. Kate563
  6. Catherine436
  7. Annie334
  8. Hannah296
  9. Julia273
  10. Maggie222

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

Spellings

Spellings

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

Spelling190119111926Records
Regan6,2705,9034,924Search
O'Regan1,1831,5722,352Search

Related forms

  • Regan — The same name without the O; Gaois gives O'Regan and Regan as equal main English forms.[3][1]
  • Reagan, O'Reagan — Spellings reflecting the spoken form Ó Réagáin; Wiktionary also derives Reagan from the Irish.[2][4][13]
  • O Regan, Ragon — Other spellings listed by Wikipedia as cognates.[11]
  • O'Riegaine, O'Regane — Early English renderings recorded by Woulfe.[1]

Diaspora

The O'Regans abroad

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

SpellingPeopleUS rank
Regan21,9511642nd
O'Regan1,13022689th

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

Heraldry

Is there a O'Regan coat of arms?

Arms were granted to individuals and particular families, so there is no O'Regan 'family crest' shared by everyone of the name. We found no entry under O'Regan or Regan in the copy of Burke's General Armory (1884) we consulted, and no other source used here records arms for either the Brega or the Thomond family. Arms sold online for the surname should be treated with caution.[14]

Websites selling a single “O'Regan 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'Regan

  • Anthony O'Regan (1809–1866)
    Mayo-born president of St Jarlath's College, Tuam, and Catholic Bishop of Chicago from 1854 to 1858.
  • Ronald Reagan (1911–2004)
    40th US President, great-grandson of Michael O'Regan of Ballyporeen, Co. Tipperary.
  • Brendan O'Regan (1917–2008)
    Businessman who developed Shannon Airport and is credited with inventing the duty-free shop.
  • Donald Regan (1918–2003)
    US Treasury Secretary and later White House Chief of Staff under Ronald Reagan.
  • Gerald Regan (1928–2019)
    Canadian politician who served as Premier of Nova Scotia from 1970 to 1978.
  • Tipene O'Regan (born 1939)
    New Zealand academic and company director, former chairman of the Ngāi Tahu Māori Trust Board.
  • Kate O'Regan (born 1957)
    Former judge of South Africa's Constitutional Court, later director of Oxford's Bonavero Institute.
  • Daithí Regan (born 1968)
    Birr hurler who played for Offaly from 1989 to 1999, later a broadcaster.
  • Seamus O'Regan (born 1971)
    Canadian broadcaster turned Liberal MP and federal cabinet minister.
  • Tarik O'Regan (born 1978)
    British and American composer, twice nominated for Grammy awards.
  • Fionn Regan (born 1981)
    Bray-born folk singer-songwriter known for his debut album The End of History.

Questions

Questions about the O'Regan name

Is O'Regan an Irish surname?

Yes. O'Regan is the English form of the Gaelic Ó Riagáin, 'descendant of Riagán'. It was borne by two separate families: lords of south Brega in Meath, counted among the Four Tribes of Tara, and a Dalcassian family of Thomond. After the Meath family lost its lands following the Anglo-Norman invasion, the name spread across Ireland.[1][2][7]

What is O'Regan in Irish?

The standard Irish form is Ó Riagáin. Woulfe notes that in speech it was often said Ó Réagáin, and he also records the variant Ó Réigín. All of these were anglicised O'Regan or Regan. The older annal spelling is Ua Riagáin.[1][4][5][3]

Are O'Regan and Regan the same name?

Yes. Both come from Ó Riagáin, and Gaois treats them as equal English forms. Woulfe records both spellings for each variant of the Irish name, so the O prefix does not distinguish one family from another, and the same family may be found under either form in records.[3][1][11]

Is Reagan the same name as O'Regan?

Yes, Reagan is a spelling of the same Irish name, reflecting the spoken form Ó Réagáin. Ronald Reagan's great-grandfather, Michael O'Regan, was baptised at Ballyporeen, Co. Tipperary, in 1829 and changed the spelling to Reagan in London before emigrating to Illinois in 1857.[2][4][12]

What does O'Regan mean?

It means 'descendant of Riagán'. Woulfe gives no meaning for the personal name itself. Wikipedia suggests it may be built on rí, 'king' or 'sovereign', with a diminutive ending, giving something like 'little king', but this is a likely explanation rather than a settled one.[1][2]

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

Not one that belongs to everyone named O'Regan. Arms were granted to particular people and families, and the sources used for this page, including Burke's General Armory of 1884, record no arms for the O'Regans of Brega or of Thomond. Treat any single 'O'Regan crest' sold online with caution.[14]

Where does the O'Regan name come from?

One family came from south Brega, around Tara in Co. Meath and the north of Co. Dublin, where they were lords until the late 12th century. The other was Dalcassian, from Thomond, the O'Brien country centred on Co. Clare. Woulfe found O'Regans common all over Ireland by the early 20th century.[1][9][2]

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

In the 1911 census the largest numbers of O'Regans lived in Cork (3,338), Roscommon (965), Mayo (677). Relative to population, the name was most concentrated in Roscommon (103 per 10,000), Cork (85 per 10,000), Mayo (35 per 10,000).

How common was the O'Regan surname in Ireland?

7,475 people were recorded as Regan or O'Regan in the 1911 census of Ireland, making it the 90th most common surname. That is roughly 0.2% of the population, or 1 person in 588.

Looking for a O'Regan ancestor?

Search every O'Regan 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, Ó Riagáin, in Irish Names and Surnames (1923)
  2. Wikipedia, O'Regan (2026)
  3. Gaois research group, Dublin City University, Sloinnte: Irish surname data (version 2) (2022). Cluster 'Riagán': Ó Riagáin, Ó Réagáin; O'Regan, Regan.
  4. Patrick Woulfe, Ó Réagáin, in Irish Names and Surnames (1923)
  5. Patrick Woulfe, Ó Réigín, in Irish Names and Surnames (1923)
  6. Wikipedia, Amlaíb mac Sitriuc (2026)
  7. Wikipedia, Four Tribes of Tara (2026)
  8. Wikipedia, Cennétig mac Lorcáin (2026)
  9. Wikipedia, Kings of Brega (2026)
  10. Wikipedia, The Song of Dermot and the Earl (2026)
  11. Wikipedia, Regan (2026)
  12. Wikipedia, Jack Reagan (2026)
  13. Wiktionary, Reagan (2026)
  14. Sir Bernard Burke, The General Armory of England, Scotland, Ireland, and Wales (1884). Searched for O'Regan, Regan and Reagan; no entry found in the archive.org text.
  15. 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.