Càstro

surname · Latin script

Càstro is a surname written in the Latin script, with more bearers in the United States than in any other country. In the Philippines it is the 32nd most common surname. Recorded meaning: From Old Galician-Portuguese castro, from Latin castrum. Cognate with Portuguese castro, Spanish castro. See also alcázar, borrowed from Spanish, which entered through Arabic.

rarermore common
  • ECEcuador1 in 136(measured from records)
  • ESSpain1 in 406
  • USUnited States1 in 1.8K

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)

184,134 people, 2010

#852 (measured from records)

of 19M surnames

Sources
498 (measured from records)

Highest-authority source

1 in 65 (inferred from the name graph)

Costa Rica

measured from records inferred from the name graph

Name dossier (print, CSV)

Spellings & scripts(measured from records)

One other spelling is counted as the same name:

Locally spelled Castro in US United States, PH Philippines, AR Argentina 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)

Derivation of Càstro: each step is the form the one above it came from.
Càstro
  1. Old Galician-Portuguesecastro(measured from records)
  2. Latincastrum(measured from records)

From Old Galician-Portuguese castro, from Latin castrum. Cognate with Portuguese castro, Spanish castro. See also alcázar, borrowed from Spanish, which entered through Arabic.

Sources 7

  • A dictionary of surnames
  • Dizionario dei cognomi italiani
  • The Oxford Dictionary of Family Names in Britain and Ireland
  • 국립국어원 외래어 표기 용례 자료 (NIKL loanword/foreign-name transcription examples)
  • Wiktionary

Attested across 23 languages in the etymology graph.

Where in the world(measured from records)

Càstro 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.

Where Càstro is recorded, by country
CountryMost common spellingSources
US United States#323184,1341 in 1.8K188KCastro498
AR Argentina—148,2161 in 307148KCastro5
EC Ecuador—123,8851 in 136124KCastro62
ES Spain#885123,1561 in 406123KCastro150
CR Costa Rica—78,7551 in 6579K—4
UY Uruguay—40,0261 in 8540K—2
PH Philippines#32≈1 est.≈1 in 73M—Castro169

184,134 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; Census Bureau — Surname Frequency 2020; RENAPER — Apellidos (person counts, national); INEC — civil registry names; INE — Padrón per-token widgets (current living counts, given + apellidos); INE — Apellidos más frecuentes (Padrón Municipal); TSE — electoral roll (padrón) names; INE Uruguay — Apellidos más frecuentes 1902–2024 (Tableau Public). 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 names spelled this way(inferred from the name graph)

Càstro is also recorded as another name, grouped separately because the records behind them do not connect to the one described above.

  • Spanish surname95 spellings in the group

    Most recorded in Mexico, Brazil, Argentina, Peru

    Languages: Spanish, Portuguese, Arabic

    Also written Castro, Castró, Кастро, Cäströ, Caströ

1 further group record this spelling and are not listed here.

Grouping is the name graph's, not a register's: two spellings join a group when the evidence links them, so a group is a claim about the records rather than about the people.

Evidence(measured from records)

No register attests this spelling yet

None of the official registers or reference works in our corpus lists Càstro under this spelling. The statistics on this page rest on person records, and the related names are inferred from the name graph.

Frequently asked questions

What does the name Càstro mean, and where does it come from?
From Old Galician-Portuguese castro, from Latin castrum. Cognate with Portuguese castro, Spanish castro. See also alcázar, borrowed from Spanish, which entered through Arabic. Recorded by A dictionary of surnames and Dizionario dei cognomi italiani and 5 other sources.
In which country does Càstro have the most bearers?
In the United States, the national register counted about 184 thousand people named Càstro, more than in any other country we hold, where it is most often spelled castro.
Where is Càstro most common?
Measured as a share of residents rather than as a count, Càstro is densest in Costa Rica — about 1 in 65 people — even though United States holds more of our records for it.
How common is the name Càstro?
In the United States, the national register counted 184,134 people named Càstro in 2010, about 1 in 1.8 thousand residents.
How common is Càstro compared with other names?
In the United States, Càstro is the 323rd most common surname of 6,282,806 surnames recorded there.

What do you want to know about Càstro?

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Query this name via API
curl -H "X-API-Key: YOUR_KEY" https://api.mondonomo.ai/api/v1/name-graph/c%C3%A0stro

The 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, “Càstro” — the 323rd most common surname in United States. Data snapshot 2026-10-10.

See how Càstro parses inside a full name →