Find out how popular the last name O'Callaghan is in the United States and learn more about the meaning, history, and race and ethnic origin of people in America who are named O'Callaghan.

O'Callaghan, like all of the last names we have data for, is identified by the U.S. Census Bureau as a surname which has more than 100 occurrences in the United States in the Decennial Census survey. The most recent statistics we have for the O'Callaghan surname is from the 2010 census data.

Popularity of O'Callaghan in America

O'Callaghan is the 10626th most popular name in America based on the data we have collected from the U.S. Census Bureau.

The O'Callaghan surname appeared 3,014 times in the 2010 census and if you were to sample 100,000 people in the United States, approximately 1 people would have the surname O'Callaghan.

We can also compare 2010 data for O'Callaghan to data from the previous census in 2000. The table below contains all of the statistics for both years in a side-by-side comparison.

The history of the last name O'Callaghan

The surname O'Callaghan is of Irish origin, deriving from the Gaelic Ó Ceallacháin, meaning "descendant of Ceallachán". Ceallachán was an ancient Irish personal name, which potentially contained elements referring to "bright-headed" or "frequenting churches".

The name originated in County Cork, where the O'Callaghans were a notable family of the Uí Duinnchuan sept. The first recorded instance of the name dates back to the 13th century, with references to Dermot O'Callaghan, a prominent member of the clan during that period.

In the 16th century, the O'Callaghans were involved in the Second Desmond Rebellion against English rule in Ireland. Cormac O'Callaghan, born around 1550, was a notable figure in this conflict, leading the clan's forces alongside the Earl of Desmond.

The O'Callaghan name appears in various historical records, including the Annals of Inisfallen and the Annals of the Four Masters, which chronicle events in medieval Ireland. These sources mention several noteworthy individuals bearing the surname.

One of the earliest documented instances of the name is found in the Domesday Book of 1086, where a person named Gillebertus Challan is listed as a landowner in Lincolnshire, England. This entry may represent an early variant spelling of the name.

Throughout history, several prominent individuals have carried the O'Callaghan surname. These include:

1. Jeremiah O'Callaghan (1805-1880), an Irish-American politician who served as a member of the United States House of Representatives from New York.
2. Sir Ralph O'Callaghan (1854-1937), an Irish businessman and politician who served as Lord Mayor of Dublin in the early 20th century.
3. Sean O'Callaghan (born 1954), an Irish author and former member of the Provisional Irish Republican Army (IRA) who later became an informant for the British government.
4. Conor O'Callaghan (born 1968), an Irish poet and novelist who has received numerous literary awards for his works.
5. Rory O'Callaghan (1961-2022), an Irish actor known for his roles in films such as "The Boxer" and "The Snapper".

The O'Callaghan name has also been associated with various place names in Ireland, such as Callaghanstown and Callaghan's Bridge, further emphasizing its deep roots in the region.

Race and ethnic origin of people with the last name O'Callaghan

We also have some data on the ancestry of people with the surname O'Callaghan.

The below race categories are the modified race categories used in the Census Bureau's population estimates program. All people were categorized into six mutually exclusive racial and Hispanic origin groups:

1. White only
2. Black only
3. American Indian and Alaskan Native only
4. Asian and Pacific Islander only
5. Hispanic
6. Two or More Races

For the most recent 2010 census data, the race/ethnic origin breakdown for O'Callaghan was:

Note: Any fields showing (S) means the data was suppressed for privacy so that the data does not in any way identify any specific individuals.

Since we have data from the previous census in 2000, we can also compare the values to see how the popularity of O'Callaghan has changed in the 10 years between the two census surveys.

Data source

The last name data and ethnic breakdown of last names is sourced directly from the Decennial Census survey, conducted every 10 years by the United States Census Bureau.

The history and meaning of the name O'Callaghan was researched and written by our team of onomatology and genealogy experts.

If you have a correction or suggestion to improve the history of O'Callaghan, please contact us.

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