Show ContentsO'Reilly Surname History

The O'Reilly surname originally appeared in Gaelic as Ó Raghailligh, which means descendant of Raghallach.

Early Origins of the O'Reilly family

The surname O'Reilly was first found in County Cavan. They were known as the Princes of East Breffny, descended from Raghallaigh, Prince of Breffny in 981. They maintained their territory during the Anglo/Norman invasion of Strongbow, Earl of Pembroke, in 1172, but Sir John O'Reilly, Prince of Breffny surrendered the principality to Queen Elizabeth I thereby ensuring that his territories remained intact.

Early History of the O'Reilly family

This web page shows only a small excerpt of our O'Reilly research. Another 95 words (7 lines of text) covering the years 1598, 1630, 1640, 1646, 1667, 1669, 1689, 1691, 1695 and 1703 are included under the topic Early O'Reilly History in all our PDF Extended History products and printed products wherever possible.

O'Reilly Spelling Variations

Irish names were rarely spelled consistently in the Middle Ages. Spelling variations of the name O'Reilly dating from that time include O'Reilly, O'Reilley, O'Reily, O'Rielly, O'Riely, O'Riley, O'Rilley, Reel and many more.

Early Notables of the O'Reilly family

Notable amongst the family name at this time was

  • Count John O'Reilly; Edmund O'Reilly (1598-1669), Roman Catholic Archbishop of Armagh; Hugh Reily (Reilly or O’Reilly) (c.1630-1695) Irish Member of Parliament for Cavan Borough in the Patriot Parliam...

O'Reilly World Ranking

In the United States, the name O'Reilly is the 3,584th most popular surname with an estimated 7,461 people with that name. 1 However, in Australia, the name O'Reilly is ranked the 664th most popular surname with an estimated 5,882 people with that name. 2 And in New Zealand, the name O'Reilly is the 867th popular surname with an estimated 845 people with that name. 3 The United Kingdom ranks O'Reilly as 905th with 7,573 people. 4


United States O'Reilly migration to the United States +

To escape the religious and political discrimination they experienced primarily at the hands of the English, thousands of Irish left their homeland in the 19th century. These migrants typically settled in communities throughout the East Coast of North America, but also joined the wagon trains moving out to the Midwest. Ironically, when the American War of Independence began, many Irish settlers took the side of England, and at the war's conclusion moved north to Canada. These United Empire Loyalists, were granted land along the St. Lawrence River and the Niagara Peninsula. Other Irish immigrants settled in Newfoundland, the Ottawa Valley, New Brunswick and Nova Scotia. The greatest influx of Irish immigrants, however, came to North America during the Great Potato Famine of the late 1840s. Thousands left Ireland at this time for North America and Australia. Many of those numbers, however, did not live through the long sea passage. These Irish settlers to North America were immediately put to work building railroads, coal mines, bridges, and canals. Irish settlers made an inestimable contribution to the building of the New World. Early North American immigration records have revealed a number of people bearing the Irish name O'Reilly or a variant listed above, including:

O'Reilly Settlers in United States in the 19th Century
  • Alexander, Bernard, Christopher, James, Patrick, Terence, and Thomas O'Reilly, who arrived in Philadelphia, Pennsylvania, between 1840 and 1860
O'Reilly Settlers in United States in the 20th Century
  • Alice O'Reilly, aged 24, who immigrated to America from Dublin, in 1900
  • Alma O'Reilly, aged 9, who landed in America, in 1903
  • Andrew O'Reilly, aged 22, who immigrated to the United States from Cootehill High Briagan, Ireland, in 1906
  • A. E. O'Reilly, aged 21, who settled in America from London, England, in 1909
  • Alice O'Reilly, aged 30, who landed in America from Carrigan, Ireland, in 1910
  • ... (More are available in all our PDF Extended History products and printed products wherever possible.)

Canada O'Reilly migration to Canada +

Some of the first settlers of this family name were:

O'Reilly Settlers in Canada in the 19th Century
  • Thomas O'Reilly, who arrived in Saint John, New Brunswick aboard the ship "Protector" in 1834

Australia O'Reilly migration to Australia +

Emigration to Australia followed the First Fleets of convicts, tradespeople and early settlers. Early immigrants include:

O'Reilly Settlers in Australia in the 19th Century
  • Mr. Philip O'reilly, (b. 1807), aged 41, irish shop keeper who was convicted in County Leitrim, Ireland for 7 years for sedition (he wrote a letter relative to bad landlords), transported aboard the "Blenheim" on 1st November 1848, arriving in Tasmania (Van Diemen's Land), he was given a Ticket of Leave almost immediatley on arrival 5
  • Michael O'Reilly, aged 24, who arrived in South Australia in 1854 aboard the ship "Sir Thomas Gresham" 6
  • John Boyle O'Reilly (1844-1890), Irish convict who arrived in Western Australia aboard the ship "Hougoumont", the last convict ship in 1868

New Zealand O'Reilly migration to New Zealand +

Emigration to New Zealand followed in the footsteps of the European explorers, such as Captain Cook (1769-70): first came sealers, whalers, missionaries, and traders. By 1838, the British New Zealand Company had begun buying land from the Maori tribes, and selling it to settlers, and, after the Treaty of Waitangi in 1840, many British families set out on the arduous six month journey from Britain to Aotearoa to start a new life. Early immigrants include:

O'Reilly Settlers in New Zealand in the 19th Century
  • Rev. John James Purcell O'Reilly, British settler travelling from London and Plymouth aboard the ship "Thomas Sparks" arriving in Wellington, New Zealand on 31st January 1843, the ship stuck rocks of the coast of Cape of Good Hope delaying her landing by 2 months 7
  • John O'Reilly, aged 25, a labourer, who arrived in Auckland, New Zealand aboard the ship "Eveline" in 1865 8
  • Mr. John O'Reilly, South African settler travelling from Cape Town aboard the ship "Eveline" arriving in Auckland, New Zealand on 22nd January 1865 9

Contemporary Notables of the name O'Reilly (post 1700) +

  • Mary Margaret O'Reilly (1865-1949), American Assistant Director of the United States Bureau of the Mint
  • Charles Francis O'Reilly, American founder of O'Reilly Auto Parts in 1957, now with 4,100 stores throughout the United States
  • William James "Bill" O'Reilly Jr. (b. 1949), American television host, author, syndicated columnist, best known for his political commentary program The O'Reilly Factor on the Fox News Channel
  • Tim O'Reilly (b. 1954), Irish-born, American founder of O'Reilly Media, known for his support of free software and open source movements
  • Heather O'Reilly (b. 1985), American soccer player, three-time Olympic Gold medalist
  • David J. O'Reilly (b. 1947), American former Chairman and CEO of Chevron Corporation
  • Samuel O'Reilly (d. 1908), American inventor of the modern tattoo gun
  • Robert O'Reilly (b. 1950), American actor
  • Leonora O’Reilly (1870-1927), American feminist, suffragist, and trade union organizer
  • Bernard O’Reilly (1824-1894), Irish-born prelate of the Roman Catholic Church, 3rd Bishop of Liverpool (1873-1894)
  • ... (Another 15 notables are available in all our PDF Extended History products and printed products wherever possible.)

HMS Hood
  • Mr. Dennis P O'Reilly (b. 1921), English Stoker 2nd Class serving for the Royal Navy from Eastbourne, Sussex, England, who sailed into battle and died in the HMS Hood sinking 10
SS Southern Cross
  • Mr. Ambrose O'Reilly (1894-1914), Newfoundlander from Goulds who was aboard the "SS Southern Cross" when it is suspected she sank between the 31st March 1914 and early April during the storm with a heavy load of pelts; no survivors were ever found


  1. "What are the 5,000 Most Common Last Names in the U.S.?". NameCensus.com, https://namecensus.com/last-names/
  2. "Most Common Last Names in Australia." Forebears, https://forebears.io/australia/surnames
  3. "Most Common Last Names in New Zealand." Forebears, https://forebears.io/new-zealand/surnames
  4. "UK surname ranking." UK Surname map, https://www.surnamemap.eu/unitedkingdom/surnames_ranking.php?p=10
  5. Convict Records Voyages to Australia (Retrieved 15th October 2020). Retrieved from https://convictrecords.com.au/ships/blenheim
  6. South Australian Register Monday 20th March 1854. (Retrieved 2010, November 5) Sir Thomas Gresham 1854. Retrieved http://www.theshipslist.com/ships/australia/sirthomasgresham1854.shtml
  7. New Zealand Yesteryears Passenger Lists 1800 to 1900 (Retrieved 26th March 2019). Retrieved from http://www.yesteryears.co.nz/shipping/passlist.html
  8. New Zealand Yesteryears Passenger Lists 1800 to 1900 (Retrieved 4th November 2011). Retrieved from http://www.yesteryears.co.nz/shipping/passlist.html
  9. New Zealand Yesteryears Passenger Lists 1800 to 1900 (Retrieved 17th October 2018). Retrieved from http://www.yesteryears.co.nz/shipping/passlist.html
  10. H.M.S. Hood Association-Battle Cruiser Hood: Crew Information - H.M.S. Hood Rolls of Honour, Men Lost in the Sinking of H.M.S. Hood, 24th May 1941. (Retrieved 2016, July 15) . Retrieved from http://www.hmshood.com/crew/memorial/roh_24may41.htm


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