O'Brien
surname · Latin script
(measured from records)Officially recorded in 21 countries · latest register: Surnames of England and Wales (taliesin-arlein.net, Sept 2002 electoral register), 2002
/əbɹajən/(machine-generated) pronunciation, model-generated
O'Brien is a surname written in the Latin script, with more bearers in the United States than in any other country. In Ireland it is the 8th most common surname. Recorded meaning: Anglicisation of the Irish surname Ó Briain, meaning “descendant of Brian”.
- IEIreland≈1 in 914(inferred from the name graph)
- AUAustralia≈1 in 1.6K
- GBUnited Kingdom≈1 in 2.3K
carrying the name, as counted by its national register where one exists and as Mondonomo estimates it elsewhere (marked ≈ and "est." on hover). One hue, darker where it is more common; hover a country for its figure.
- United States (measured from records)
- #610 (measured from records)
- 3 (measured from records)
- Record sources
- 491 (measured from records)
- ≈1 in 914 (inferred from the name graph)
118,557 people, 2010
of 19M surnames, spellings grouped
recorded for this name
corpus datasets behind its best-documented spelling
strongest: highest-authority source
Ireland, est.
measured from records inferred from the name graph
Spellings & scripts
(measured from records)One other spelling is counted as the same name:
Locally spelled Obrien in US United States, GB United Kingdom, NZ New Zealand and 2 more.
Spellings marked ● are how people bearing the name write it in our records, and ○ marks a model's transliteration; click a spelling to open its page.
Meaning & origin
(measured from records)Anglicisation of the Irish surname Ó Briain, meaning “descendant of Brian”.
Cited for this meaning 1
Attested in 1 language in the etymology graph.
Where in the world
(measured from records)O'Brien counted together with the spellings and other-language forms grouped with it. Where a register counted another spelling, the row names it.
Sorted by bearers: national registers' counts, and Mondonomo's estimates (≈, est.) where no register counts.
| Country | Most common spelling | Sources | ||||
|---|---|---|---|---|---|---|
| US United States | #200 | 118,557 | 1 in 2.8K | 119K | Obrien | 491 |
| GB United Kingdom | #109 | ≈29,000 est. | ≈1 in 2.3K | 42K | Obrien | 250 |
| AU Australia | #66 | ≈16,000 est. | ≈1 in 1.6K | — | O'Brien | 212 |
| EG Egypt | — | ≈15,000 est. | ≈1 in 6.9K | — | Obrien | 12 |
| ID Indonesia | — | ≈14,000 est. | ≈1 in 19K | — | Obrien | 30 |
| IE Ireland | #8 | ≈5,700 est. | ≈1 in 914 | — | O'Brien | 149 |
| NZ New Zealand | #99 | ≈2,100 est. | ≈1 in 2.4K | — | Obrien | 99 |
118,557 people counted by Census Bureau — Surname Frequency 2010, 2010. Exact figures are national registers' own counts, while figures marked ≈ and est. are Mondonomo’s estimates, counted from our sources and calibrated against those registers; hover one for how far to trust it in that country. A dash means neither exists.
Registers cited: Census Bureau — Surname Frequency 2010; Surnames of England and Wales (taliesin-arlein.net, Sept 2002 electoral register). Figures without a register are Mondonomo estimates; see Methodology.
Country figures for a list of names, at full precision, are available under licence rather than by scraping this table (how that works).
Notable people with this name
(measured from records)- Edmond O'Brienb. 1915USnot in their usual nameAmerican actor (1915–1985)
- Dusty Springfieldb. 1939GBnot in their usual nameBritish singer (1939–1999)
- Anne Riceb. 1941USnot in their usual nameAmerican author (1941–2021)
- Richard O'Brienb. 1942GBnot in their usual nameEnglish actor, writer, musician, and television presenter
- Tim O'Brienb. 1946USnot in their usual nameAmerican novelist (born 1946)
- Peter O'Brienb. 1960AUnot in their usual nameAustralian actor (1960-)
- Conan O'Brienb. 1963USnot in their usual nameAmerican television show host and comedian
- Dan O'Brienb. 1966USnot in their usual nameAmerican athlete
- Liam O'Brienb. 1976USnot in their usual nameAmerican voice actor, writer, and director
- Dylan O'Brienb. 1991USnot in their usual nameAmerican actor (born 1991)
The ten people covered by the most Wikipedia language editions — a proxy for cross-cultural notability, which favours historical and Western figures over equally prominent contemporary ones — shown by birth year. Source: Wikidata (CC0).
How to address them
(machine-generated)Evidence
(measured from records)26 registers and reference works attest this spelling, across 21 countries.
| Country | Register | Year | Count | Rank |
|---|---|---|---|---|
| GB United Kingdom | Surnames of England and Wales (taliesin-arlein.net, Sept 2002 electoral register) | 2002 | 42K | #136 |
| US United States | wru Name Dictionary — US surnames, voter-file supplement (Khanna et al.) | — | — | — |
Reference works 3
- Nederlandse FamilienamenBank (Dutch surname bank; ex-Meertens Instituut, now CBG)2007
- Wikipedia surname tokens
- Wikidata name items (native-script + romanized given/family names)
These works list the name; their figures are licensed and are not reproduced here.
Register rows as of the 2026-10-09 data build.
Frequently asked questions
- What does the name O'Brien mean, and where does it come from?
- Anglicisation of the Irish surname Ó Briain, meaning “descendant of Brian”. Recorded by Wiktionary.
- How do you pronounce O'Brien?
- A machine transcription gives /əbɹajən/ (IPA) for English.
- In which country does O'Brien have the most bearers?
- In the United States, the national register counted about 119 thousand people named O'Brien, more than in any other country we hold, where it is most often spelled obrien.
- How common is the name O'Brien?
- In the United States, the national register counted 118,557 people named O'Brien in 2010, about 1 in 2.8 thousand residents.
- How common is O'Brien compared with other names?
- In the United States, O'Brien is the 200th most common surname of 6,282,806 surnames recorded there.
What do you want to know about O'Brien?
Nobody replies to these one by one, but what readers ask decides what these pages answer next.
Query this name via API
curl -H "X-API-Key: YOUR_KEY" https://api.mondonomo.ai/api/v1/name-graph/o'brienThe payload this page is built from: spellings and scripts, countries and languages, related names, and the registers that attest the form. It takes a free API key (1,000 requests a day), which returns what this page shows everyone; the full country table, every register citation and the year-by-year series come with a licensed key, as does bulk access.
About this data
measured from records inferred from the name graph machine-generated
These figures come from the data snapshot of and will change as it is rebuilt.
Statistics are aggregated from the Mondonomo name corpus; related names and etymology are inferred from the name graph; pronunciation and any machine-marked transliterations are model-generated. Read how the numbers are made, including their known failure modes, and where the data comes from.
Reference works we consult — surname dictionaries, official name registers, Wikidata and Wiktionary — are named directly, beside the claims they support. The per-country source counts also include datasets of person records: we publish how many there are and their authority tier, but not their names.
Cite this page Mondonomo, “O'Brien” — the 200th most common surname in United States. Data snapshot 2026-10-13.