Find out how popular the last name O'Brien 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'Brien.

O'Brien, 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'Brien surname is from the 2010 census data.

Popularity of O'Brien in America

O'Brien is the 258th most popular name in America based on the data we have collected from the U.S. Census Bureau.

The O'Brien surname appeared 118,557 times in the 2010 census and if you were to sample 100,000 people in the United States, approximately 40 people would have the surname O'Brien.

We can also compare 2010 data for O'Brien 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'Brien

The surname O'Brien originates from Ireland and is a deeply rooted name in Irish history. It is derived from the Gaelic Ó Briain, meaning "descendant of Brian." The name can be traced back to the 10th century and is associated with the powerful Dál gCais clan, rulers of the Kingdom of Munster.

One of the earliest recorded bearers of the name was Brian Boru, an Irish king who reigned from 976 to 1014. He is renowned for his victory over the Vikings at the Battle of Clontarf in 1014. His descendants adopted the surname O'Brien and played a significant role in Irish history throughout the Middle Ages.

The O'Briens were prominent in various historical records, including the Annals of Inisfallen and the Book of Leinster. These manuscripts chronicle their exploits and influence across Ireland. The O'Briens were also mentioned in the Annals of the Four Masters, a 17th-century chronicle of medieval Irish history.

The O'Brien surname has been associated with several notable figures throughout history. Murrough O'Brien (1614-1674) was a prominent Irish soldier and politician who served as the 6th Baron Inchiquin. Lucius O'Brien (1800-1872) was a politician and author who served as the 13th Baron Inchiquin. William Smith O'Brien (1803-1864) was a renowned Irish revolutionary and leader of the Young Ireland movement.

Other notable individuals with the O'Brien surname include Edna O'Brien (born 1930), an acclaimed Irish novelist and playwright, and Conor O'Brien (1884-1952), an Irish mathematician and philosopher. The name has also been linked to various place names in Ireland, such as Bunratty Castle, the ancestral home of the O'Briens in County Clare.

While the O'Brien surname is predominantly Irish, it has also been adopted by families in other parts of the world, including England, Scotland, and the United States. However, its roots can be firmly traced back to the ancient Irish kingdom of Munster and the Dál gCais dynasty, making it a prominent and historically significant surname in Irish genealogy.

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

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

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'Brien 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'Brien 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'Brien 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'Brien, please contact us.

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