O'Reilly (Irish: Ó Raghallaigh) is a group of families, ultimately all of Irish Gaelic origin, who were historically the kings of East Bréifne in what is today County Cavan. The clan were part of the Connachta's Uí Briúin 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 Irish surnames.
It is also the patronymic form of the Irish name Reilly (Irish Gaelic: Uí Raghaile). It 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.
It is usually anglicised as Reilly, Riley and O'Reilly. The original form of the name, Ó Raghallaigh, denotes "from/of Raghallach", the name Raghallach thought to be derived from the compounds ragh (meaning "race") and ceallach (meaning "sociable").
The Ó Raghallaigh family were part of the Connachta, with the eponymous Raghallach said to have died at the Battle of Clontarf in 1014. The family became the kings of East Breifne, modern-day County Cavan and County Longford.
The name is common and widespread throughout Ireland, ranked 8th most common in 1890 and 11th in 1996.
People with the surname O'Reilly include:
Alejandro O'Reilly (1722–1794), second Spanish governor of colonial Louisiana
Bernard O'Reilly (1903–1975), located the wreck of a Stinson aircraft in the McPherson Range, Australia, 1937
Bernard O'Reilly (bishop of Hartford) (1803–1856), Roman Catholic bishop
Bernard O'Reilly (bishop of Liverpool) (1824–1894), Roman Catholic bishop
Bill O'Reilly (1949–), American commentator and television show host of The O'Reilly Factor on the Fox News Channel
Bill O'Reilly, Australian cricketer
Bob O'Reilly, Australian rugby league footballer
Caitriona O'Reilly, poet and critic
Cal O'Reilly, Canadian ice hockey player
Cameron O'Reilly, Irish and Australian businessman
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 including
David O'Reilly, film director and artist
David J. O'Reilly, Chairman and CEO of Chevron Corporation
Dermot O'Reilly (1942–2007), Singer and songwriter in band Ryan's Fancy, contributed strongly to the Music of Newfoundland and Labrador.
Des O'Reilly (1954–2016), Australian rugby league player
Emily O'Reilly, Irish journalist
Emma O'Reilly, Irish physiotherapist and cycling soigneur, bullied and sued by Lance Armstrong.
Finbarr O'Reilly, Canadian photographer
Gary O'Reilly, English footballer
Genevieve O'Reilly, Irish actress
Heather O'Reilly (1985–), American soccer player
Hugh Reily (1630–1695), Irish M.P. and political author
Ian O'Reilly, (1999–), Actor "Moone Boy"
James Reilly (Canadian politician) (1835–1909), Canadian businessman and politician from Alberta
James O'Reilly, American Roman Catholic priest
John Reyly (recte O'Reilly) (c.1646 – 17 February 1717) was an M.P. for Cavan County (Parliament of Ireland constituency) in the Parliament of Ireland of 1689, known as the Patriot Parliament.
John O'Reilly, Leader of The Saint Patrick's Battalion of Mexico
John O'Reilly (1940–), Canadian politician from Ontario
Joseph O'Reilly, Irish politician
Kyle O'Reilly (1987–), ring name of Canadian professional wrestler Kyle Greenwood
Leonora O'Reilly, an American feminist
Luke O'Reilly (disambiguation)
Mary Margaret O'Reilly, Assistant Director of the United States Bureau of the Mint from 1924 to 1938
Margaret M. O'Reilly (1962– ), Irish-born, American art curator, New Jersey State Museum
Matthew O'Reilly, Irish politician and farmer
Peter O'Reilly (civil servant) (1827–1905), settler and official in the Colony of British Columbia
Peter O'Reilly (hurler) (1902–1940), Irish hurler
Philip O'Reilly (c.1600–1655), M.P. for County Cavan
Philip Og O'Reilly (c. 1640–1703) was an M.P. for Cavan Borough in the Parliament of Ireland of 1689, known as the Patriot Parliament.
Philip Reyley (recte O'Reilly) (b. c.1630 – d. after 1689) was an M.P. for Cavan County (Parliament of Ireland constituency) in the Parliament of Ireland of 1689, known as the Patriot Parliament.
Randall C. O'Reilly (1967–), professor of psychology, developer of Leabra
Robert O'Reilly (1950–), American actor
Ryan O'Reilly (ice hockey) (1991–), Canadian ice hockey player
Ryan O'Reilly (wrestler) (1980–), American professional wrestler
Samuel O'Reilly (19th century), American inventor
Stephen O'Reilly, American actor
Stephen O'Reilly, Australian footballer
Terry O'Reilly, hockey player
Tom O'Reilly (1915–1995), Irish Fianna Fáil politician
Tim O'Reilly (1954–), 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 (1936–), Irish businessman
Valli O'Reilly, Makeup artist
Walter Cresswell O'Reilly (1877–1954), Australian Commonwealth Film Censor and founding President of the National Trust of Australia
O'Reilly Lords of Bréifne c.1161–1607
Christopher O'Riley (born 1956), American classical pianist and public radio show host
Don O'Riley (1945–1997), Major League Baseball pitcher
Bunny Wailer (born 1947), reggae musician sometimes known as Bunny O'Riley
Jon Riley (1824–1879), US army deserter also known as John O'Riley
Aaron Riley (born 1980), American mixed martial artist
Ali Riley (born 1987), American-born New Zealand soccer player
Andy Riley (born 1970), British writer and cartoonist
Arthur Riley (born 1903), South African footballer
Audrey Riley, English cellist
B. Daniel Riley (1946–2016), American politician
Bennett C. Riley (1790–1853), American military governor of California before it became a US state
Bernard Riley (born 1981), American football player
Bill Riley (born 1950), Canadian ice hockey player
Billy Riley, English catch wrestling instructor
Billy Lee Riley (1933–2009), American musician
Ben Riley (born 1933), American jazz drummer
Bob Riley (born 1944), American politician, Governor of Alabama
Bob Riley, founder of race car company Riley & Scott
Bob C. Riley (1924–1994), American politician, briefly Governor of Arkansas in 1975
Boots Riley, American vocalist
Bridget Riley (born 1931), British op-art painter
Bridgett Riley (born 1973), American boxer
Burke Riley (1914–2006), American state legislator
Charles Owen Leaver Riley (1854–1929), the first Anglican Archbishop of Perth
Charles Valentine Riley (1843–1895), American entomologist
Charley Riley, American boxer
Charlotte Riley (born 1981), English actress
Chris Riley, American USL Second Division soccer player
Chris Riley (golfer) (born 1973), professional American golfer
Chris Riley (priest) (born 1954), Australian Priest and prominent youth worker
Christopher Riley (born 1967), English writer and film maker
Daniel Aloysius Riley (1916–1984), Canadian politician
Dave Riley, American musician
Delbert Riley, Canadian First Nations leader
Denise Riley (born 1948), English professor of literature
Dorothy Comstock Riley (1924–2004), American lawyer and judge
Doug Riley, Canadian musician
Eric Riley (born 1970), American basketball player
Frank Riley, American athlete
Freida J. Riley (1937–1969), American math and science teacher
Gary Riley (born 1963), American actor
Gillian Riley (born 1945), English writer and authority on Italian cuisine
Gina Riley (born 1961), Australian actor, writer, singer and comedian
Gwendoline Riley (born 1979), English writer
Harold Riley (artist) (born 1934), English artist
Harold William Hounsfield Riley (1877–1946), Canadian politician from Alberta
Hayden Riley (1921–1995), American college sports coach
Herbert D. Riley (1904–1973), United States Navy admiral
Herlin Riley (born 1957), American jazz drummer
Herman Riley (1933–2007), American saxophone player
Isaac Riley (1852–1926), Canadian politician
Ivan Riley (1900–1943), American Olympic athlete
Jack Riley (actor) (1935–2016), American comedian and actor
Jack Riley (ice hockey b. 1910) (1910–1994), Irish ice hockey player
Jack Riley (ice hockey b. 1919) (born 1919), Canadian ice hockey player
James Riley (Captain) Captain of the American merchant ship Commerce
James Riley (soccer player) (born 1982), American soccer winger for the New England Revolution
James Whitcomb Riley (1849–1916), American writer and poet
Jason Riley (journalist) (born 1971), American journalist
Jeannie C. Riley (born 1945), American country and gospel music singer
Jim Riley (American football) (born 1945), American football player
Jo Riley or Josephine Riley (born 20th century), UK writer, translator, actor, specialised in Chinese theatre
Joe Riley (artist) (1964–2007), US artist, special effects artist, SubGenius
Joe Riley (hockey) (1923–1976), US ice hockey player
Joe Riley (rugby league), British rugby league footballer
John Riley (poet) (1937–1978), English poet associated with the British Poetry Revival
John H. Riley (1947–1994), American attorney and railroad transportation administrator
John J. Riley (1895–1962), American politician, US Representative from South Carolina
John P. Riley, Jr. or Jack Riley (born 1920), American ice hockey coach
Jon Riley (1805–1850), Irish-American US Army officer who deserted to fight for Mexico in the Mexican war
Jonathon Riley (athlete) (born 1978), American middle- and long-distance runner
Jonathon Riley (British Army officer) (born 1955), British Army officer
Joseph Albert Riley (1869–1940), South Australian sports administrator
Joseph Harvey Riley (1873–1941), US ornithologist, Smithsonian Institution
Joseph P. Riley, Jr. (born 1943), US politician, Charleston mayor
Julia Riley, English astrophysicist
Karon Riley (born 1978), American football player
Ken Riley (born 1947), American football player
Kent Riley, English actor
Larry Riley (actor) (1952–1992), American actor
Lawrence Riley (1896–1974), American playwright
Lawrence Joseph Riley, American Roman Catholic bishop
Lisa Riley (born 1976), English actress and broadcaster
Malcolm Riley (born 1960), British musician and author
Marc Riley (born 1961), British musician, critic, and disc jockey
Mark Riley (American radio host) (born 1951), American radio host
Mark Riley, Australian television presenter
Martin Riley (basketball) (born 1954), former Canadian basketball player
Martin Riley (cricketer) (1851–1899), Yorkshire cricketer
Martin Riley (footballer) (born 1988), English professional football defender
Matt Riley (born 1979), American baseball player
Melanie Riley (born 1968), British businessperson
Michael Riley (born 1962), Canadian actor
Michael Riley (artist) (1960–2004), Australian artist
Mike Riley (born 1952), American college football coach
Nancy Riley (born 1958), American state senator
Pat Riley (born 1945), American professional basketball coach
Patrick T. Riley, American political theorist
Paul Riley, Scottish actor and comedian
Peter Riley (born 1940), English poet
Quintin Riley (1905–1980), British Arctic explorer
Rachel Riley (born 1986), English television (Countdown) presenter
Raven Riley (born 1986), American adult-film actress
Richard Riley (born 1933), American politician, Governor of South Carolina 1979–1987
Rob Riley (disambiguation)
Ronald Riley (born 1947), Australian Olympic field hockey player
Ruth Riley (born 1979), American basketball player
Ryan Max Riley (born 1979), American humorist and skier
Sam Riley (born 1980), English actor
Samantha Riley (born 1972), Australian swimmer
Sean Riley (American football) (born 1974), American football player
Steve Riley, American accordionist, singer
Steve Riley (drummer) (born 1956), American drummer
Talulah Riley (born 1985), English actress
Teddy Riley (jazz) (1924–1992), American jazz trumpeter
Teddy Riley (producer) (born 1967), American producer, singer, songwriter, and musician
Terry Riley (born 1935), American composer
Thomas Riley (disambiguation)
Trevor Riley (born 1948), Australian judge
Victor Riley (born 1972), American football player
Wayne Riley (born 1962), Australian golfer
William Riley (disambiguation)
Fictional people:
Mr. O'Reilly, Fictitious Irish character/builder portrayed by the Irish actor David Kelly on the episode "The Builders" from Fawlty Towers
Riley family, fictional family in TV series One Life to Live
Aloysius Umbongo N'Danga O'Reilly, fictitious character in the song "Baguette Dilemma for the Booker Prize Guy" by the band Half Man Half Biscuit on their 2014 album Urge for Offal
Joe Riley, leading protagonist of the family on the show
Joe Riley (James Dunn), in the movie The Golden Gloves Story (1951)
Joe Riley (Eddie Quillan), in the movie Jungle Raiders (1945)
Kevin Riley, recurring junior officer character in Star Trek: The Original Series
Cpl. Scott Riley, character in Call of Duty: United Offensive
O'Reilly Auto Parts, an American chain of automotive supply stores
O'Reilly Media (formerly O'Reilly & Associates), an American media company
Baba O'Riley, a song by The Who
