O'Reilly () is a common

Irish surname A formal Irish name consists of a given name and a surname. In the Irish language, most surnames are patronymic surnames (distinct from patronymic, patronyms, which are seen in Icelandic names for example). The form of a surname varies according ...

. The O'Reillys were historically the kings of East Bréifne in what is today

County Cavan County Cavan ( ; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Provinces of Ireland, province of Ulster and is part of the Northern and Western Region. It is named after the town of Cavan and is based on the hi ...

. The clan were part of the

Connachta The Connachta are a group of medieval Irish dynasty, dynasties who claimed descent from the legendary High King of Ireland, High King Conn of the Hundred Battles, Conn Cétchathach (Conn of the Hundred Battles). The modern western Provinces of ...

Uí Briúin The Uí Briúin were a royal dynasty of Connacht. Their eponymous apical ancestor was Brión, son of Eochaid Mugmedon and Mongfind, and an elder half brother of Niall of the Nine Hostages. They formed part of the Connachta, along with th ...

Bréifne kindred and were closely related to the Ó Ruairc (O'Rourkes) of West Bréifne. O'Reilly is ranked tenth in the top twenty list of most common Irish surnames. It is also the

patronymic A patronymic, or patronym, is a component of a personal name based on the given name of one's father, grandfather (more specifically an avonymic), or an earlier male ancestor. It is the male equivalent of a matronymic. Patronymics are used, b ...

form of the Irish name Reilly (). The name is commonly found throughout Ireland, with the greatest concentration of the surname found in County Cavan followed by Longford, Meath, Westmeath, Fermanagh and Monaghan, and the Province of Leinster.

Naming conventions

Overview

Usually anglicised as Reilly, O'Reilly or Riley, the original form of the name, Ó Raghallaigh, denotes "descendant of Raghallach". The Ó Raghallaigh family were part of the

, with the

eponymous An eponym is a noun after which or for which someone or something is, or is believed to be, named. Adjectives derived from the word ''eponym'' include ''eponymous'' and ''eponymic''. Eponyms are commonly used for time periods, places, innovati ...

Raghallach said to have died at the

Battle of Clontarf The Battle of Clontarf () took place on 23 April 1014 at Clontarf, near Dublin, on the east coast of Ireland. It pitted an army led by Brian Boru, High King of Ireland, against a Norse- Irish alliance comprising the forces of Sigtrygg Silkbea ...

in 1014. The family became

the kings The Kings are a Canadian rock band formed in 1977 in Oakville, Ontario. They are best known for their 1980 song "This Beat Goes On/Switchin' To Glide", which was a hit in the United States and Canada. Recording history The Kings were formed in ...

East Breifne The Kingdom of East Breifne or Breifne O'Reilly (; , ) was an historic kingdom of Ireland roughly corresponding to County Cavan that existed from 1256 to 1607 in Ireland, 1607. It took its present boundaries in 1579 in Ireland, 1579 when East Br ...

, modern-day

and

County Longford County Longford () is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Provinces of Ireland, province of Leinster. It is named after the town of Longford. Longford County Council is the Local government in the Republic ...

. The name is common and widespread throughout Ireland, ranked 11th most common in 1890 and in 1997. A self-proclaimed and disputed O'Reilly Clan Chieftain to this day is at odds with the O'Rourke Clan Chieftain because he contests the recognised O'Rourke claim on the title Prince of Breifne. This was settled in 1994 when the Chief Herald of Ireland made the O'Rourke Chief the Prince of

Breifne The Kingdom of Breifne or Bréifne (), anglicized as Breffny, was a medieval overkingdom in Gaelic Ireland. It comprised what is now County Leitrim, County Cavan and parts of neighbouring counties, and corresponds roughly to the Roman Catho ...

, but the Office of the Chief Herald stopped granting courtesy titles to Gaelic Chiefs in 2003 (see O'Rourke).

People with the surname

O'Reilly

People with the surname O'Reilly include: * Alejandro O'Reilly (1722–1794), second Spanish governor of colonial Louisiana * Andreas O'Reilly (1742–1832), Irish-born Austrian general * Bernard O'Reilly (1903–1975), Australian author, found the wreck of a Stinson aircraft in the McPherson Range, 1937 * Bernard O'Reilly (bishop of Hartford) (1803–1856), Irish Roman Catholic bishop * Bernard O'Reilly (bishop of Liverpool) (1824–1894), Irish Roman Catholic bishop * Bill O'Reilly (born 1949), American commentator and television show host of

The O'Reilly Factor ''The O'Reilly Factor'' (originally titled ''The O'Reilly Report'' and also known as ''The Factor'') is an American cable television news and talk show. ''The O'Reilly Factor'' first aired in the United States on Fox News Channel on October 7 ...

on the Fox News Channel * Bill O'Reilly, Australian cricketer * Bob O'Reilly, Australian rugby league footballer * Caitriona O'Reilly, Irish poet and critic * Cal O'Reilly, Canadian ice hockey player *

Cameron O'Reilly Anthony Cameron O'Reilly, generally known as Cameron O'Reilly, (born 28 April 1964) is a Dublin-born businessman with Irish and Australian citizenship, the son of an Irish father, media magnate Tony O'Reilly and an Australian mother, Susan Came ...

, Irish and Australian businessman * Cassia O'Reilly, Irish singer-songwriter * Charles O'Reilly (died 1800), Roman Catholic Bishop of Kilmore from 1798 to 1800 * Danny O'Reilly, lead singer of Irish band, The Coronas * David O'Reilly, several people * Dermot O'Reilly (1942–2007), Irish-born Canadian singer and songwriter in band Ryan's Fancy, working in Newfoundland and Labrador * Des O'Reilly (1954–2016), Australian rugby league player * Devin O'Reilly, Canadian Irish dancer *

Emily O'Reilly Emily O'Reilly is an author and former journalist and broadcaster who became Ireland's first female Ombudsman in 2003, succeeding Kevin Murphy. On 3 July 2013, she was voted European Ombudsman by the European Parliament. She was re-elected ...

, Irish journalist * Emma O'Reilly, Irish physiotherapist and cycling soigneur who worked for Lance Armstrong * Eugenia O'Reilly-Regueiro, Mexican mathematician * Finbarr O'Reilly, Canadian photographer * Gary O'Reilly, English footballer *

Genevieve O'Reilly Genevieve O'Reilly (born 6 January 1977) is an Irish-born Australian actress. She is best known for portraying Mon Mothma in the '' Star Wars'' franchise beginning with ''Revenge of the Sith'' (2005), a role which earned her a Saturn Award nom ...

, Irish actress * Heather O'Reilly (born 1985), American soccer player * Hugh Reily (1630–1695), Irish M.P. and political author * James Reilly (Canadian politician) (1835–1909), Canadian businessman and politician from Alberta * James O'Reilly, American Roman Catholic priest * Jennifer O'Reilly (1943–2016), medieval historian of Britain and Ireland * Jenny Quinn O'Reilly (1762–1802), in baptism Evgenia Ivanovna Vyazemskaya, Irish-born lady and second wife of Prince Andrey Vyazemsky, mother of the Russian Imperial poet Pyotr Vyazemsky * Joe O'Reilly, Irish politician * John Reyly (recte O'Reilly) (c. 1646–1717), M.P. for Cavan County in the Parliament of Ireland of 1689 * John B. O'Reilly Jr. (1948–2025), American politician from Michigan * John O'Reilly (born 1940), Canadian politician from Ontario * Kyle O'Reilly (born 1987), ring name of Canadian professional wrestler Kyle Greenwood * Leonora O'Reilly, American feminist * Luke O'Reilly (disambiguation), several people *

Mary Margaret O'Reilly Mary Margaret O'Reilly (October14, 1865December6, 1949) was an American civil servant who served as the assistant director of the United States Bureau of the Mint from 1924 until 1938. One of the United States government's highest-ranking fem ...

, assistant director of the United States Bureau of the Mint from 1924 to 1938 * Matthew O'Reilly, Irish politician and farmer * O'Reilly, Lords of Bréifne (c. 1161 – 1607), Irish rulers * Patrick Thomas O'Reilly (1833–1892), U.S. Catholic bishop, born in Ireland * Peter O'Reilly (civil servant) (1827–1905), Irish-born settler and official in the Colony of British Columbia * Peter O'Reilly (hurler) (1902–1940), Irish hurler * Philip O'Reilly (Cavan County MP) (c. 1600–1655), M.P. for County Cavan * Philip Og O'Reilly (c. 1640 – 1703), M.P. for Cavan Borough in the Parliament of Ireland of 1689 * Philip Reyley (recte O'Reilly) (c. 1630 – after 1689), M.P. for Cavan County in the Parliament of Ireland of 1689 * Randall C. O'Reilly (born 1967), American professor of psychology, developer of Leabra * Robert O'Reilly (born 1950), American actor * Ruth O'Reilly (born 1981), Irish rugby union player * Ryan O'Reilly (ice hockey) (born 1991), Canadian ice hockey player * Ryan O'Reilly (wrestler) (born 1980), American professional wrestler * Sam O'Reilly (born 2006), Canadian ice hockey player * Samuel O'Reilly (1854–1909), American tattoo artist and inventor * Stephen O'Reilly (born 1964) (better known as Stephen Egerton), American musician * Stephen O'Reilly, American actor * Stephen O'Reilly, Australian footballer * Terry O'Reilly, Canadian hockey player *

Tim O'Reilly Timothy O'Reilly (born 6 June 1954) is an Irish-American author and publisher, who is the founder of O'Reilly Media (formerly O'Reilly & Associates). He popularised the terms open source and Web 2.0. Education and early life Born in County Co ...

(born 1954), Irish-American founder of O'Reilly Media * Tom O'Reilly (1915–1995), Irish Gaelic footballer and politician * Tom O'Reilly, Irish Sinn Féin politician * Tom O'Reilly, Papua New Guinea international *

Tony O'Reilly Sir Anthony John Francis O'Reilly (7 May 1936 – 18 May 2024) was an Irish businessman and international rugby union player. He was known for his try scoring in rugby, his involvement in the Independent News & Media Group, which he led from ...

(1936–2024), Irish businessman * Valli O'Reilly, American makeup artist * Walter Cresswell O'Reilly (1877–1954), Australian Commonwealth Film Censor and founding President of the National Trust of Australia

O'Riley

* Bunny Wailer (1947–2021), Jamaican reggae musician sometimes known as Bunny O'Riley * Christopher O'Riley (born 1956), American classical pianist and public radio show host * Don O'Riley (1945–1997), American Major League Baseball pitcher * Jon Riley (1824–1879), US army deserter also known as John O'Riley * Matt O'Riley (born 2000), English footballer at Celtic F.C.

Ní Raghallaigh

* Shónagh Ní Raghallaigh, Irish politician

Riley

Fictional characters with the surname

* Mr. O'Reilly, portrayed by the Irish actor David Kelly in the ''

Fawlty Towers ''Fawlty Towers'' is a British television sitcom written by John Cleese and Connie Booth, originally broadcast on BBC Two in 1975 and 1979. Two series of six episodes each were made. The series is set in Fawlty Towers, a dysfunctional fictional ...

'' episode " The Builders" * Aloysius Umbongo N'Danga O'Reilly, in the song "Baguette Dilemma for the Booker Prize Guy" by the band

Half Man Half Biscuit Half Man Half Biscuit are an English rock band, formed in 1984 in Birkenhead, Merseyside. Known for their satirical, sardonic, and sometimes surreal songs, the band comprises lead singer and guitarist Nigel Blackwell, bassist and singer Neil Cr ...

on their 2014 album '' Urge for Offal'' *Corporal Walter "Radar" O'Reilly, in the '' M*A*S*H'' media franchise

References

External links

The O'Reilly ClanO'Reilly family pedigree
at Library Ireland
O'Reilly, Reilly, Riley. History of familyIrish Times surname entry for "Riley"The Irish O'Reilly family and their connections to Austria and Russia
by Stefan M. Newerkla {{DEFAULTSORT:Oreilly Irish families Surnames of Irish origin Anglicised Irish-language surnames English-language surnames Patronymic surnames