Brennan
surname · Latin script
Meaning: from Irish Gaelic O Braondin, meaning ‘descendant of Braondn’, a personal name literally ‘little drop of moisture’
Recorded as a male name· opposite-gender records fall within measured source noise
/bɹɛnən/(machine-generated) pronunciation, model-generated
Brennan 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 36th most common surname.
- IEIreland≈1 in 895(inferred from the name graph)
- AUAustralia≈1 in 2.6K
- GBUnited Kingdom≈1 in 3.4K
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)
- Sources
- 502 (measured from records)
- ≈1 in 895 (inferred from the name graph)
49,238 people, 2010
Highest-authority source
Ireland, est.
measured from records inferred from the name graph
Meaning & origin(measured from records)
from Irish Gaelic O Braondin, meaning ‘descendant of Braondn’, a personal name literally ‘little drop of moisture’
Sources 1
- Encyclopedia of surnames [the complete companion to tracing your names history]
Attested across 2 languages in the etymology graph.
Where in the world(measured from records)
Brennan 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 | #518 | 49,238 | 1 in 6.8K | 49K | Brennan | 502 |
| GB United Kingdom | #300 | ≈19,000 est. | ≈1 in 3.4K | 3 | Brennan | 281 |
| AU Australia | #224 | ≈9,800 est. | ≈1 in 2.6K | 3 | Brennan | 221 |
| CA Canada | #451 | ≈7,300 est. | ≈1 in 5.1K | 1 | Brennan | 203 |
| IE Ireland | #36 | ≈5,800 est. | ≈1 in 895 | — | Brennan | 162 |
| NZ New Zealand | #404 | ≈1,100 est. | ≈1 in 4.6K | — | Brennan | 98 |
| JM Jamaica | #166 | ≈620 est. | ≈1 in 4.6K | — | Brennan | 4 |
49,238 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; NRS — Baby names Scotland full list (1974–present); Australian national given names (aggregated state BDM); Alberta Open Government — Frequency and Ranking of Baby Names by Year and Gender. 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).
Other recorded senses(measured from records)
Brennan is also recorded in 5 other lexicons, as a different name or as an ordinary word. These are senses of the spelling, not of the name above.
In English, from 'burn hand', a nickname for the officer who carried out harsh punishment; also possibly Irish Ó Braonáin; first attested Reginald Brennehand' 12th DC (L)
as a nameA Dictionary of English Surnames
In English, O Braonain ‘little drop’; sept of Kilkenny, Kerry and Westmeath
as a nameIrish family names
‘descendant of Braondn', a personal name from a dim. of braon moisture, drop; cf. Breen. Brearley see Brierley Breassell see Brazil Vars.: Brebner see Brabham O’Brennan, (O’)Brenane, (O’)Brinan(e), Brannan; Brennand. Brecht see Albert
as a nameThe Oxford Names Companion - The definitive guide to Surnames, First Names, and Place Names of the British Isles
In English, William Joseph, Jr., US Supreme
as a namePronouncing Dictionary of Proper Names
In English, Court justice
as a namePronouncing Dictionary of Proper Names
Ordered by how much of this spelling's record each language holds, so a sense from a language the name is barely used in sits last rather than first.
Notable people with this name(measured from records)
- Walter Brennanb. 1894USAmerican actor (1894–1974)
- William J. Brennanb. 1906USU.S. Supreme Court justice from 1956 to 1990
- Eileen Brennanb. 1932USAmerican actress and singer (1932–2013)
- Colleen Brennanb. 1949USAmerican pornographic actress (born 1949)
- Brid Brennanb. 1955GBBritish actress
- John O. Brennanb. 1955USDirector of the Central Intelligence Agency from 2013 to 2017
- Kathleen Brennanb. 1955USIrish–American songwriter, musician producer & artist
- Enyab. 1961IEnot in their usual nameIrish singer (born 1961)
- Megan Brennanb. 1961US74th United States Postmaster General
- Ian Brennanb. 1978USAmerican screenwriter, producer, director and actor
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)
Attested in 54 sources across 26 countries.
| Country | Register | Year | Count | Rank |
|---|---|---|---|---|
| US United States | Census Bureau — Surname Frequency 2010 | 2010 | 49K | #701 |
| US United States | Census Bureau — Surname Frequency 2000 | 2000 | 48K | #642 |
| US United States | Census Bureau — Surname Frequency 2020 | 2020 | 48K | #697 |
| GB United Kingdom | A Dictionary of Surnames (Hanks & Hodges, 1988) | — | — | — |
| US United States | wru Name Dictionary — US surnames, Census 2010 subset (Khanna et al.) | — | — | — |
Reference works 6
- Dictionary of American Family Names
- Nederlandse FamilienamenBank (Dutch surname bank; ex-Meertens Instituut, now CBG)2007
- Wikipedia given-name tokens
- Wikipedia surname tokens
- Wikidata name items (native-script + romanized given/family names)
- Rymut, Słownik nazwisk współcześnie w Polsce używanych (10 vols, IJP PAN, Kraków 1992–1994) — every Polish surname in the PESEL register at the end of 1990, with bearer counts nationally and per voivodeship1990
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 are other forms of the name Brennan?
- In the etymology graph, Brannon is a form of the same name in other languages.
- In which country does Brennan have the most bearers?
- In the United States, the national register counted about 49 thousand people named Brennan, more than in any other country we hold, where it is most often spelled brennan.
- How do you pronounce Brennan?
- A machine transcription gives /bɹɛnən/ (IPA) for English.
- What does the name Brennan mean, and where does it come from?
- from Irish Gaelic O Braondin, meaning ‘descendant of Braondn’, a personal name literally ‘little drop of moisture’ Recorded by Encyclopedia of surnames [the complete companion to tracing your names history].
- How common is the name Brennan?
- In the United States, the national register counted 49,238 people named Brennan in 2010, about 1 in 6.8 thousand residents.
- How common is Brennan compared with other names?
- In the United States, Brennan is the 518th most common surname of 6,282,806 surnames recorded there.
What do you want to know about Brennan?
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/brennanThe 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, “Brennan” — the 518th most common surname in United States. Data snapshot 2026-10-10.