2000
#234
National surname rank
Recorded bearers 115,385
First available Census row
Per 100,000 42.77
Common Last name
Obrien
Derived from the Irish Gaelic "Ó Briain," meaning "descendant of Brian," a name meaning "high" or "noble."
According to the 2020 US Census Bureau surname tables, roughly 132,501 Americans carry the last name Obrien. That puts it at #261 in the national surname ranking, appearing at a frequency of 38.66 per 100,000 people (about 1 in 2,587 residents).
This page is the full Name Census profile for the Obrien surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
For British records, Name Census UK has a British surname profile for Obrien with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
133K
1 in 2,587
Census rank
#261
2020 decennial data
Per 100,000
38.7
Frequency rate
Recorded bearers
116K
common in the US
Popularity narrative
The Census Bureau recorded 115,547 bearers of the surname Obrien in its 2020 decennial surname file. At a rate of 38.66 per 100,000 residents, it holds the 261st position in the national surname ranking.
Among Census respondents with the surname Obrien, the largest self-reported group is White at 91.1%. The next largest groups are Hispanic (3.4%) and Two or More Races (2.9%).
Origin
Meaning and origin of Obrien
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.
Demographics
Ancestry and ethnicity for Obrien
Among Census respondents with the surname Obrien, the largest self-reported group is White at 91.1%. The next largest groups are Hispanic (3.4%) and Two or More Races (2.9%).
The bar chart below shows how Obrien bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Obrien surname at the time of the 2020 Census, not any inherent property of the name itself.
- White91.1% · 105,267
- Hispanic or Latino3.4% · 3,905
- Two or more races2.9% · 3,383
- Black or African American1.3% · 1,527
- Asian and Pacific Islander1.0% · 1,115
- American Indian and Alaska Native0.3% · 350
Timeline
Historical Census data for Obrien
Obrien appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#258
National surname rank
Recorded bearers 118,557
+3,172 bearers (+2.7%)
Per 100,000 40.19
Rank movement Down 24 places
2020
#261
National surname rank
Recorded bearers 115,547
-3,010 bearers (-2.5%)
Per 100,000 38.66
Rank movement Down 3 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #234 | 115,385 | 42.77 | First available Census row | First available Census row |
| 2010 | #258 | 118,557 | 40.19 | +3,172 bearers (+2.7%) | Down 24 places |
| 2020 | #261 | 115,547 | 38.66 | -3,010 bearers (-2.5%) | Down 3 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Obrien surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #258 | #261 | -1.2% |
| Count | 118,557 | 115,547 | -2.5% |
| Per 100K | 40.19 | 38.66 | -3.8% |
Between the 2010 and 2020 Census, the number of Obrien bearers went from 118,557 to 115,547 (-2.5% change). The surname moved down 3 positions in the national ranking, going from #258 to #261.
Notable bearers
Famous people with the surname Obrien
FAQ
Obrien surname: questions and answers
How many people in the U.S. have the surname Obrien?
Name Census estimates that about 132,501 living Americans carry the surname Obrien. Using the current population baseline, that works out to roughly 1 in 2,587 residents.
How common is Obrien?
Obrien ranks #261 in the 2020 Census surname tables and is classified on this site as "Common." The Census recorded the name at a frequency of 38.66 per 100,000 residents, which is about 39 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 115,547 people with the surname Obrien. That is different from the site's living-bearer estimate (132,501), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 38.66 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 38.66 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 39 of them to have the surname Obrien.
Has Obrien become more or less common over time?
Between 2010 and 2020, the surname Obrien went from 118,557 recorded bearers to 115,547. That is a decrease of 3,010 (-2.5%). In the national ranking it fell from #258 to #261.
What does the Census say about the background of Obrien?
Among Census respondents with the surname Obrien, the largest self-reported group is White at 91.1%. The next largest groups are Hispanic (3.4%) and Two or More Races (2.9%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
White is the largest self-reported group for the surname Obrien in the 2020 Census, accounting for 91.1% (105,267 people in the source table).
What is the full ancestry breakdown?
Obrien appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (91.1%), Hispanic (3.4%), Two or More Races (2.9%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Obrien (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Obrien mean?
Derived from the Irish Gaelic "Ó Briain," meaning "descendant of Brian," a name meaning "high" or "noble." The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Obrien (38.66 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people are called Obrien?
If you just want to know how many people have the surname Obrien, HowManyOfMe.org gives you the headline number in one glance.