Ó Ceallacháin, O'Callaghan, or simply Callaghan without the prefix, is an Irish surname. Often when Irish immigrants migrated to the United States and passed through Ellis Island the "g" was removed from the spelling.
Origin and meaning
The surname means descendent of Ceallachán who was the Eóganachta King of Munster from AD 935 until 954. The personal name Cellach means 'bright-headed'. The principal Munster sept of the name Callaghan were lords of Cineál Aodha in South Cork originally. This area is west of Mallow along the Blackwater river valley. The family were dispossessed of their ancestral home and 24,000 acres (97 km2) by the Cromwellian Plantation and settled in East Clare. In 1994, Don Juan O'Callaghan of Tortosa was recognised by the Genealogical Office as the senior descendant in the male line of the last inaugurated O'Callaghan.
The Callaghan land near Mallow, forfeited by Donough O'Callaghan after the Irish rebellion of 1641, came into the hands of a family called Longfield or Longueville, which built a 20-bedroom Georgian mansion there. In a twist of history, 500 acres (2.0 km2) of the ancient Callaghan land returned to Callaghan hands in the twentieth century, when Longueville House was bought by a descendant of Donough O'Callaghan. The ancestral estate of the Callaghans, now a luxury hotel, is currently owned by William O'Callaghan.
An entirely different sept, Ó Ceileacháin in Irish, is to be found in the counties Armagh, Louth, Meath and Monaghan. It has been anglicised as Callaghan, Kelaghan, Keelaghan, Kealahan and other variants. In County Meath, where it is widespread but has been found mainly in the parishes of Kells, Trim and Athboy, it is mainly anglicised as Callahan, Callaghan or O'Callaghan (with local spelling variants). In County Westmeath it is still found in the form Kellaghan and Kelleghan. In County Monaghan it is often found as Keelan.
Members of the Ó Ceileacháin family were mentioned in the Annals of the Four Masters as being lords of Uí Breasail, a district on the southern shore of Lough Neagh, and priors of Armagh in the 11th century.
- Ernie Callaghan (1907-1972), Awarded M.B.E. by her Majesty The Queen for Service to the Crown.
- Tabby Callaghan (born 1981), Irish guitarist and singer songwriter
- Barry O'Callaghan, CEO and controlling shareholder of Riverdeep Interactive Learning
- Bill O'Callaghan (1868–1946), Irish hurler
- Billy O'Callaghan (born 1974), Irish short story writer
- Con O'Callaghan (decathlete) (born 1908), Ireland's first Olympic decathlete; brother of Dr. Pat O'Callaghan
- Christopher Callaghan, 2006 Republican Candidate for NY State Comptroller
- Daniel J. Callaghan (1890-1942), Rear Admiral – US Navy
- David O'Callaghan (dual player) (born 1983)
- David O'Callaghan (Kerry Gaelic footballer) (born 1987)
- Denis O'Callaghan (born 1949), Australian rules footballer
- Derry O' Callaghan, radio presenter, 'Oldies 'n Irish',Cork's 96FM.
- Donncha O'Callaghan (born 1979), Irish international rugby union player
- Edmund Bailey O'Callaghan (1797-1880), doctor, journalist, leader in the patriotic movements of both Ireland and Quebec
- Fred Callaghan (born 1944), footballer with Fulham
- Admiral of the Fleet Sir George Callaghan (1852-1920)
- Georgina Callaghan, who performs as Callaghan, British musician
- Guy Callaghan (born 1970), New Zealand butterfly swimmer
- James Callaghan (1912-2005), Prime Minister of the United Kingdom (1976–1979)
- John O'Callaghan (Medal of Honor) (1850–1899), American soldier and Medal of Honor recipient.
- John O'Callaghan (musician), Irish musician and DJ
- John O'Callaghan, lead singer of The Maine
- José O'Callaghan Martínez (1922–2001), Spanish Jesuit Catholic priest
- Joseph T. O'Callahan (1905-1964), Captain, US Navy, Jesuit priest, Medal of Honor Recipient
- Leanne Callaghan (b. 1972), British ski mountaineer and mountain climber
- Mary O'Callaghan, executive
- Miriam O'Callaghan (born 1960), RTÉ presenter; her father grew up at Callaghan's Cross, County Kerry
- Morley Callaghan (1903-1990), Canadian novelist, short story writer, playwright, TV and radio personality
- Patrick Callaghan (1879–1959), Scottish footballer
- Seán O'Callaghan (born 1954), from Tralee, County Kerry; IRA informer
- Sheila Callaghan (born 1973), American playwright
- Steve Callaghan, writer of Family Guy TV series
- Stuart Callaghan (born 1976), Scottish footballer
- Therése O'Callaghan, a camogie player captain
- William M. Callaghan (1897-1991), Admiral, US Navy; first commanding officer of the battleship Missouri
- O'Callaghans Mills County Clare Ireland
- Callaghan, New South Wales, a suburb of Newcastle, New South Wales and home of the University of Newcastle, Australia
- Liscallaghan, old Irish name for Fivemiletown, County Tyrone
- Callaghan, Virginia, a census-designated place in the United States
- Irish nobility
- Eóganacht Chaisil
- Irish royal families
- Chief of the Name
- Callahan (disambiguation)
- Callaghan (disambiguation)
- Other Munster families
- Wells, John C. (2008), Longman Pronunciation Dictionary (3rd ed.), Longman, p. 557, ISBN 9781405881180
- Longueville House
- Edward McLysaght: Irish Families, Their Names, Arms and Origins
- Annála Rioghachta Éireann: Annals of the Kingdom of Ireland
- Bugge, Alexander (ed. and tr.), Caithreim Cellachain Caisil: The Victorious Career of Cellachan of Cashel Christiania: J. Chr. Gundersens Bogtrykkeri. 1905.
- Curley, Walter J.P., Vanishing Kingdoms: The Irish Chiefs and their Families. Dublin: Lilliput Press. 2004.
- O'Hart, John, Irish Pedigrees. Dublin. 5th edition, 1892.
- O'Donoghue Seamus, Cellachan.
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