surnames.ie

Irish surname · 69th most common in 1911

Casey

Casey comes from the Irish Ó Cathasaigh, 'descendant of Cathasach', a personal name meaning 'vigilant' or 'watchful'. Woulfe records six separate families of the name, from lords of Saithne in north Co. Dublin to Munster septs in Limerick and Cork and church families in Mayo, Roscommon and Fermanagh.

Irish Ó CathasaighIrish Mac Cathasaigh
1901 census
9,325
#68 · 21 per 10,000
1911 census
9,211
#69 · 21 per 10,000
1926 census
8,524
#54 · 29 per 10,000
Most numerous
Cork
Highest share: Kerry

Language & meaning

Meaning & Irish forms

Gaelic Gaelic Irish: several unrelated septs called Ó Cathasaigh in Leinster, Munster, Connacht and Ulster, plus a small Mac Cathasaigh family in Monaghan and Armagh.[1][2][3]

Ó Cathasaigh
“descendant of Cathasach”[1][4][5]
The source of almost all Caseys, borne by several unrelated septs. Gaois gives the same spelling as the standard modern form, and Wiktionary gives the feminine as Ní Chathasaigh.
Mac Cathasaigh
“son of Cathasach”[2]
A much rarer surname of Monaghan and Armagh, also anglicised Casey and MacCasey.

The name is built on the personal name Cathasach, usually explained as “vigilant, watchful”. Woulfe and Wikipedia both give 'vigilant' or 'watchful'. Wiktionary traces it to an Old Irish adjective it glosses as 'vigilant' or 'noisy'.[1][3][5]

Pronunciation

Casey: KAY-see

Ó Cathasaigh: oh KAH-huh-see /oːˈkahəsˠiː/[5][6]

Place

Where the Caseys 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: 0.8 per 10,000 (14 people) Waterford: 33.9 per 10,000 (279 people) Dublin: 15.4 per 10,000 (739 people) Kilkenny: 8.1 per 10,000 (61 people) Carlow: 4.7 per 10,000 (17 people) Limerick: 56.4 per 10,000 (809 people) Louth: 35.1 per 10,000 (221 people) Tipperary: 29.8 per 10,000 (455 people) Roscommon: 48.2 per 10,000 (453 people) Meath: 16.9 per 10,000 (110 people) Wicklow: 4.4 per 10,000 (27 people) Cavan: 3.6 per 10,000 (33 people) Cork: 41.5 per 10,000 (1,630 people) Clare: 45 per 10,000 (470 people) Galway: 18.3 per 10,000 (334 people) Mayo: 25.1 per 10,000 (483 people) Sligo: 38.4 per 10,000 (304 people) Leitrim: 8.1 per 10,000 (51 people) Offaly: 16.2 per 10,000 (92 people) Laois: 11 per 10,000 (60 people) Kildare: 13.6 per 10,000 (91 people) Kerry: 76.3 per 10,000 (1,219 people) Monaghan: 15 per 10,000 (107 people) Wexford: 6.1 per 10,000 (62 people) Longford: 76 per 10,000 (333 people) Westmeath: 41.2 per 10,000 (248 people) Tyrone: 9.1 per 10,000 (130 people) Antrim: 3.2 per 10,000 (153 people) Armagh: 8.8 per 10,000 (105 people) Fermanagh: 1 per 10,000 (6 people) Londonderry: 3.4 per 10,000 (48 people) Down: 2.2 per 10,000 (67 people)
fewerup to 79 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

76 per 10,000

1,219 Caseys · 3.63× the national share

Highest share, 1911

  1. Kerry 76
  2. Longford 76
  3. Limerick 56
  4. Roscommon 48
  5. Clare 45
  6. Cork 42
  7. Westmeath 41
  8. Sligo 38

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
Antrim128153—33—
Armagh138105—119—
Carlow261721756
Cavan343319442
Clare475470522424555
Cork1,5961,6301,701404247
Donegal121420111
Down4967—22—
Dublin663739783151516
Fermanagh206—31—
Galway351334327181819
Kerry1,2331,2191,181747679
Kildare9891102161418
Kilkenny606153888
Laois756078131115
Leitrim6151619811
Limerick838809743575653
Londonderry5148—43—
Longford335333304727676
Louth217221218333535
Mayo488483429252525
Meath86110117121719
Monaghan17310799231515
Offaly829284141616
Roscommon496453395494847
Sligo320304265403837
Tipperary471455411293029
Tyrone136130—99—
Waterford265279267303434
Westmeath247248214404138
Wexford746284769
Wicklow272726545

Local strongholds in 1911

District Electoral Divisions (300+ residents) where Caseys made up the largest share of the population. In Mountdavis, Co. Longford, about one resident in 6 was a Casey.

DEDCountyCaseysShare
MountdavisLongford69 15.5%
LissonuffyRoscommon77 14.2%
DerryfineenCork43 9.0%
GurteenSligo119 7.3%
Cashel EastLongford38 7.2%
KerryheadKerry64 6.9%
PortroyalMayo76 6.8%
KilbehenyLimerick25 6.5%

Origins

Septs & territories

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

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

Ó Cathasaigh of Saithne

Saithne, in the north of present-day Co. Dublin · Dublin

A family of ancient Meath who were lords of Saithne until Hugh de Lacy dispossessed them in the years after the Anglo-Norman invasion. Wikipedia's short O'Casey article instead identifies Saithne with Sonagh in Co. Westmeath; Woulfe places it in north Dublin.[1][7]

Ó Cathasaigh of Coshlea

barony of Coshlea · Limerick

A Dalcassian family, that is, one belonging to the Dál gCais of Thomond, whom Woulfe places in Coshlea in south-east Co. Limerick, below the Ballyhoura and Galtee mountains.[1][8]

Ó Cathasaigh of Coillte Maibinacha

Coillte Maibinacha, near Mitchelstown · Cork

A Cork family who held a territory called Coillte Maibinacha close to Mitchelstown in north Cork. Woulfe gives no further detail.[1]

Ó Cathasaigh of Kilarduff

Kilarduff, parish of Dunfeeny, Tirawley · Mayo

A Tirawley family who were erenaghs, hereditary stewards of church lands, at Kilarduff in the parish of Dunfeeny in north Mayo.[1]

Ó Cathasaigh of Cloondara

Cloondara, parish of Tisrara · Roscommon

A Roscommon church family, formerly erenaghs of Cloondara in the parish of Tisrara.[1]

Ó Cathasaigh of Devenish

Devenish, Lower Lough Erne · Fermanagh

Erenaghs of Devenish, the island monastery on Lower Lough Erne associated with St Mo Laisse, whose round tower still stands.[1][9]

Mac Cathasaigh of Oriel

Monaghan and Armagh · Monaghan, Armagh

An old but small family. Nicholas Mac Cathasaigh was Bishop of Clogher around the middle of the 14th century, and several Armagh gentlemen of the name received pardons from Elizabeth I. Woulfe thought the name very rare by his day.[2]

The name over time

History

One name, many families

Casey is a good example of an Irish surname that arose independently in several places. Its root is the personal name Cathasach, 'vigilant' or 'watchful', and any family descended from a man of that name could become Ó Cathasaigh. Woulfe identified six such septs, in Dublin, Limerick, Cork, Mayo, Roscommon and Fermanagh, and noted that all of them still had many descendants in his day. Wikipedia similarly counts at least six septs and singles out Cork and Dublin as the main centres of the name.[1][3]

The lords of Saithne

The earliest of these families to lose its lands was the sept of Saithne. Woulfe describes them as a family of ancient Meath whose territory lay in what is now north Co. Dublin. They were displaced by Hugh de Lacy, the Anglo-Norman lord of Meath, soon after the invasion of the late 12th century. Sources differ on where Saithne was: Wikipedia's O'Casey article equates it with Sonagh in Westmeath. Burke later records arms for a Casey or Casie family at Raheny in north Dublin, though he does not connect them with the old sept.[1][7][10]

The Munster Caseys

Two septs belonged to Munster. One was Dalcassian, part of the Dál gCais of Thomond, and lived in the barony of Coshlea in south-east Limerick, a district named from its position at the foot of the mountains. The other held Coillte Maibinacha near Mitchelstown in north Cork. Between them they help explain why Casey is so familiar across the south of Ireland, and why Wikipedia names Cork as one of the strongholds of the surname.[1][8][3]

Church families in the west and north

Three more Ó Cathasaigh families were erenaghs, the hereditary stewards who managed church lands. One held Kilarduff in the parish of Dunfeeny in Tirawley, north Mayo. Another was at Cloondara in the parish of Tisrara in Roscommon. The third served Devenish, the monastic island on Lower Lough Erne in Fermanagh, traditionally founded by St Mo Laisse in the 6th century and known for its round tower. In Monaghan and Armagh a separate name, Mac Cathasaigh, produced a 14th-century Bishop of Clogher, Nicholas Mac Cathasaigh.[1][9][2]

Casey and O'Casey in modern times

Like most Ó surnames, Casey generally lost its prefix in English, though O'Casey survives. The playwright Seán O'Casey was born John Casey in Dublin. After joining the Gaelic League in 1906 and learning Irish, he took the Irish form of his name, Seán Ó Cathasaigh, and later wrote as O'Casey. An earlier writer, John Keegan Casey, known as the Poet of the Fenians, wrote the song 'The Rising of the Moon' before his death in 1870.[7][6][11]

Places linked to the name

  • Saithne, Co. Dublin — Territory of the earliest recorded Ó Cathasaigh lords, lost to Hugh de Lacy after the Anglo-Norman invasion. Wikipedia places it instead at Sonagh, Co. Westmeath.[1][7]
  • Coshlea (Cois Sléibhe), Co. Limerick — Barony of the Dalcassian Ó Cathasaigh sept.[1][8]
  • Mitchelstown (Baile Mhistéala), Co. Cork — The Cork sept held Coillte Maibinacha nearby.[1]
  • Kilarduff, Dunfeeny, Co. Mayo — Church lands where a Tirawley Ó Cathasaigh family were erenaghs.[1]
  • Cloondara, Tisrara, Co. Roscommon — Church lands of the Roscommon erenagh family.[1]
  • Devenish Island (Daimhinis), Co. Fermanagh — Monastic island on Lower Lough Erne where a Casey family were erenaghs.[1][9]

Everyday lives

The Caseys in the census

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

Caseys All of Ireland Ireland's figure marked on the Casey bar

Religion, 1911

Catholic +25.4 points vs Ireland
Caseys 99.0%
All of Ireland 73.6%
Church of Ireland −12.6 points vs Ireland
Caseys 0.6%
All of Ireland 13.2%
Presbyterian −9.9 points vs Ireland
Caseys 0.2%
All of Ireland 10.1%
Methodist & other −2.9 points vs Ireland
Caseys 0.2%
All of Ireland 3.1%

Irish language

Spoke Irish, 1901 +10.6 points vs Ireland
Caseys 25.9%
All of Ireland 15.3%
Spoke Irish, 1911 +9.9 points vs Ireland
Caseys 23.4%
All of Ireland 13.5%
Spoke Irish, 1926 · 26 counties +2.6 points vs Ireland
Caseys 16.1%
All of Ireland 13.5%

97 Caseys spoke Irish only in 1901.

Reading & writing

Could read and write, 1901 · aged 15+ −2.2 points vs Ireland
Caseys 78.2%
All of Ireland 80.4%
Could read and write, 1911 · aged 15+ −1.1 points vs Ireland
Caseys 84.7%
All of Ireland 85.8%

Family life, 1911

Household size · 1,895 households about the same as Ireland
Caseys 4.79
All of Ireland 4.83
Children born per mother · women 45–59 higher than Ireland
Caseys 6.71
All of Ireland 6.46
Children still living about the same as Ireland
Caseys 80.2%
All of Ireland 79.8%

Commonest occupations

Adults aged 15+, 1901 and 1911 combined.

Farmer1,959
Farmer's son948
Farmer's daughter511
Agricultural labourer321
General labourer311
Farm servant288
Labourer225
Farm labourer179
Farmer's wife179
House keeper159

Born outside Ireland

0.9% of Caseys in 1911 gave a birthplace outside Ireland.

England51
United States23
Scotland9
Australia & NZ2
India1

Median age: 23 in 1901, 25 in 1911.

Given names

First names among the Caseys

Men and boys

  1. John2,128
  2. Patrick1,739
  3. Michael1,285
  4. James1,230
  5. Thomas1,052
  6. William651
  7. Daniel404
  8. Joseph256
  9. Martin246
  10. Peter236

Women and girls

  1. Mary2,397
  2. Bridget1,146
  3. Margaret802
  4. Ellen716
  5. Catherine586
  6. Kate423
  7. Annie355
  8. Anne299
  9. Julia275
  10. Nora266

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

Spellings

Spellings

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

Spelling190119111926Records
Casey9,3259,2118,524Search

Related forms

  • O'Casey — The form keeping the Ó prefix, used notably by the playwright Seán O'Casey.[1][7]
  • O'Cahessy — An early English spelling of Ó Cathasaigh recorded by Woulfe.[1]
  • MacCasey — From the rarer Mac Cathasaigh of Monaghan and Armagh.[2]
  • Casie — The spelling Burke uses for a Raheny family alongside Casey.[10]
  • Ní Chathasaigh — The Irish form used by women.[5]

Diaspora

The Caseys abroad

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

SpellingPeopleUS rank
Casey66,556504th

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

Heraldry

Is there a Casey coat of arms?

There is no single Casey crest, because arms belonged to particular families. Burke's General Armory records two Irish coats: one for Casey of Ireland, with a red chevron between three red eagles' heads on silver, and one for Casey or Casie of Raheny, Co. Dublin, with a gold chevron between three gold eagles' heads on blue and the motto 'Per varios casus'. Burke does not link either to a particular Ó Cathasaigh sept.[10]

Websites selling a single “Casey 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 Casey

  • Silas Casey (1807–1882)
    US Army officer who rose to major general during the American Civil War.
  • John Keegan Casey (1846–1870)
    Fenian poet and orator who wrote the song 'The Rising of the Moon'.
  • Elizabeth Owens Blackburne Casey (1848–1894)
    Irish novelist who compiled the first biographical reference book of Irish women.
  • Solanus Casey (1870–1957)
    American Capuchin friar known as a healer and spiritual counsellor.
  • Seán O'Casey (1880–1964)
    Dublin playwright and memoirist, author of The Plough and the Stars.
  • Richard Casey, Baron Casey (1890–1976)
    Australian statesman and soldier who was Governor-General of Australia from 1965 to 1969.
  • Steve Casey (1908–1987)
    Rower from Sneem, Co. Kerry, who became a world champion professional wrestler.
  • William J. Casey (1913–1987)
    American lawyer who was Director of Central Intelligence from 1981 to 1987.
  • Eamonn Casey (1927–2017)
    Bishop of Galway and Kilmacduagh from 1976 to 1992 and first chairman of Trócaire.
  • Bob Casey Sr. (1932–2000)
    Democratic governor of Pennsylvania from 1987 to 1995.
  • Karan Casey (born 1969)
    Irish folk singer and former member of the band Solas.
  • Paul Casey (born 1977)
    English professional golfer who has played on the European and PGA Tours.

Questions

Questions about the Casey name

Is Casey an Irish surname?

Yes. Casey is the English form of the Gaelic Ó Cathasaigh, 'descendant of Cathasach'. Woulfe records six distinct septs of the name, in north Dublin, Limerick, Cork, Mayo, Roscommon and Fermanagh, and a separate Mac Cathasaigh family in Monaghan and Armagh. Casey is also used as a given name, taken from the surname.[1][2][12]

What is Casey in Irish?

Ó Cathasaigh for a man and Ní Chathasaigh for a woman. The playwright Seán O'Casey, born John Casey, used the Irish form Seán Ó Cathasaigh after he learned Irish. A rarer northern surname, Mac Cathasaigh, could also become Casey in English.[1][5][6][2]

What does the name Casey mean?

It means 'descendant of Cathasach'. Woulfe and Wikipedia both translate Cathasach as 'vigilant' or 'watchful', and Wiktionary derives it from an Old Irish adjective with that sense, which could also mean 'noisy'.[1][3][5]

How do you pronounce Casey?

In English it is 'KAY-see', /ˈkeɪsi/. The Irish form Ó Cathasaigh is said roughly 'oh KAH-huh-see', transcribed /oːˈkahəsˠiː/; the 'th' is silent and sounds like an 'h'.[12][5]

Are Casey and O'Casey the same name?

Yes. Both come from Ó Cathasaigh. Most families dropped the O in English, but O'Casey survives and is the form Woulfe gives alongside Casey. The best-known example is the playwright Seán O'Casey, who was registered at birth as John Casey.[1][7][6]

Is there a Casey family crest or coat of arms?

Not for every Casey. Burke's General Armory records arms for Casey of Ireland and for Casey or Casie of Raheny, Co. Dublin, whose motto is given as 'Per varios casus'. These belonged to particular families, and Burke does not connect them to any one of the Ó Cathasaigh septs.[10]

Where does the Casey name come from?

From several places at once. Woulfe's six Ó Cathasaigh septs were the lords of Saithne in north Dublin, a Dalcassian family in Coshlea, Co. Limerick, a Cork family near Mitchelstown, and church families at Kilarduff in Mayo, Cloondara in Roscommon and Devenish in Fermanagh. A family's home county is the best clue to which line it belongs to.[1]

Where in Ireland is the Casey surname most common?

In the 1911 census the largest numbers of Caseys lived in Cork (1,630), Kerry (1,219), Limerick (809). Relative to population, the name was most concentrated in Kerry (76 per 10,000), Longford (76 per 10,000), Limerick (56 per 10,000).

How common was the Casey surname in Ireland?

9,211 people were recorded as Casey in the 1911 census of Ireland, making it the 69th most common surname. That is roughly 0.2% of the population, or 1 person in 476.

Looking for a Casey ancestor?

Search every Casey 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 Cathasaigh, in Irish Names and Surnames (1923)
  2. Patrick Woulfe, Mac Cathasaigh, in Irish Names and Surnames (1923)
  3. Wikipedia, Casey (surname) (2026)
  4. Gaois, Dublin City University, Sloinnte: Irish surnames database (cluster 'Cathasach') (2022)
  5. Wiktionary, Ó Cathasaigh (2026)
  6. Wikipedia, Seán O'Casey (2026)
  7. Wikipedia, O'Casey (2026)
  8. Wikipedia, Coshlea (2026)
  9. Wikipedia, Devenish Island (2026)
  10. Sir Bernard Burke, The General Armory of England, Scotland, Ireland, and Wales (1884). Entries 'Casey (Ireland)' and 'Casey, or Casie (Raheny, co. Dublin)'.
  11. Wikipedia, John Keegan Casey (2026)
  12. Wiktionary, Casey (2026)
  13. 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.