Hennessey
surname · Latin script
Meaning: Irish Ó hAonghusa ‘descendant of Aonghus’ (one-choice)
(measured from records)Officially recorded in 15 countries · latest register: dane.gov.pl, 2026
/ˈhɛnəsi/(machine-generated) pronunciation, model-generated
Hennessey is a surname written in the Latin script, with more bearers in the United States than in any other country.
- CRCosta Rica1 in 5.1M(measured from records)
- USUnited States1 in 36Kas Hennessy
- FIFinland1 in 133Kas Hennessy
carrying the name, as counted by each country's national register. Where a country counts another spelling of the name rather than Hennessey itself, the figure is that spelling’s, and it is named. One hue, darker where it is more common; hover a country for its figure.
- United States (measured from records)
- 2 (measured from records)
- Record sources
- 27 (measured from records)
- 1 in 5.1M (inferred from the name graph)
9,338 named Hennessy, 2010
recorded for this name
corpus datasets behind its best-documented spelling
strongest: highest-authority source
Costa Rica
measured from records inferred from the name graph
Spellings & scripts
(measured from records)Locally spelled Hennessy in US United States, PL Poland.
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)Irish Ó hAonghusa ‘descendant of Aonghus’ (one-choice).
Cited for this meaning 1
- A Dictionary of English Surnames
Where in the world
(measured from records)Hennessey 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 | 9,338as Hennessy | 1 in 36K | 9.3K | Hennessy | 20 |
| ES Spain | 65as Hennessy | 1 in 769K | 65 | — | — |
| PL Poland | 47as Hennessy | 1 in 815K | 27 | Hennessy | 9 |
| FI Finland | 42as Hennessy | 1 in 133K | 42 | — | — |
| SE Sweden | 36as Hennessy | 1 in 283K | 36 | — | — |
| CH Switzerland | 29as Hennessy | 1 in 290K | 29 | — | — |
| DK Denmark | 17as Hennessy | 1 in 345K | 17 | — | — |
| CR Costa Rica | 1 | 1 in 5.1M | 1 | — | — |
9,338 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; dane.gov.pl — PESEL living persons (surnames); INE — Padrón per-token widgets (current living counts, given + apellidos); INE — Apellidos más frecuentes (Padrón Municipal); DVV — Nimipalvelu (Finnish name service, per-name lookup); Skatteverket — Sök hur många som har ett visst namn (living population); BFS — Familiennamen der Wohnbevölkerung (surnames); Danmarks Statistik — Hvor mange hedder...? (living-population name counts); TSE — electoral roll (padrón) names. 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)- John Hennesseyb. 1900USAmerican tennis player (1900–1981)
- Dorothy Hennesseyb. 1913USAmerican activist (1913–2008)
- Mike Hennesseyb. 1928GBBritish pianist and author
- Dan Hennesseyb. 1942CACanadian actor
- Terry Hennesseyb. 1942GBWelsh footballer (1942-2025)
- Gail Hennesseyb. 1951USAmerican writerand teacher
- Robert Francis Hennesseyb. 1952USCatholic bishop
- Brad Hennesseyb. 1980USAmerican baseball pitcher
- Patrick Hennesseyb. 1982GBBritish barrister, author, journalist and former British Army officer
- Wayne Hennesseyb. 1987GBWelsh association football player (born 1987)
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)29 registers and reference works attest this spelling, across 15 countries.
| Country | Register | Year | Count | Rank |
|---|---|---|---|---|
| US United States | Census Bureau — Surname Frequency 2010 | 2010 | 8.4K | #4,245 |
| US United States | Census Bureau — Surname Frequency 2000 | 2000 | 8K | #4,076 |
| US United States | Census Bureau — Surname Frequency 2020 | 2020 | 7.7K | #4,451 |
| ES Spain | INE — Apellidos más frecuentes (Padrón Municipal) | — | 20 | #84,939 |
| ES Spain | INE — Padrón per-token widgets (current living counts, given + apellidos) | — | 20 | #83,413 |
| PL Poland | dane.gov.pl — PESEL living persons (surnames) | 2026 | 8 | — |
| PL Poland | dane.gov.pl — PESEL living persons (names) | — | 8 | #152,416 |
| CH Switzerland | BFS — Familiennamen der Wohnbevölkerung (surnames) | 2024 | 5 | #101,952 |
| SE Sweden | Skatteverket — Sök hur många som har ett visst namn (living population) | — | 5 | #53,099 |
| PL Poland | dane.gov.pl — PESEL living persons (surnames) | 2026 | 3 | — |
| PL Poland | dane.gov.pl — PESEL living persons (names) | — | 3 | #262,166 |
| DK Denmark | Danmarks Statistik — Hvor mange hedder...? (living-population name counts) | — | 3 | #78,507 |
Reference works 5
- Dictionary of American Family Names
- The Oxford Dictionary of Family Names in Britain and Ireland
- 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 Hennessey mean, and where does it come from?
- Irish Ó hAonghusa ‘descendant of Aonghus’ (one-choice). Recorded by A Dictionary of English Surnames.
- How do you pronounce Hennessey?
- A machine transcription gives /ˈhɛnəsi/ (IPA) for English.
- In which country does Hennessey have the most bearers?
- In the United States, the national register counted about 9.3 thousand people named Hennessy, more than in any other country we hold.
- Where is Hennessey most common?
- Measured as a share of residents rather than as a count, Hennessey is densest in Costa Rica — about 1 in 5.1 million people — even though United States holds more of our records for it.
- How common is the name Hennessey?
- In Costa Rica, the national register counted 1 people named Hennessey, about 1 in 5.1 million residents.
What do you want to know about Hennessey?
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/hennesseyThe 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, “Hennessey”. Data snapshot 2026-10-13.