Rex
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Meaning
means 'king'
The story
Rex means king in Latin, but its loudest modern roar came through a mixture of languages. Museum president Henry Fairfield Osborn named Tyrannosaurus rex by joining Greek words for tyrant lizard to the Latin royal title. The result, tyrant lizard king, gave a fossil animal a name dramatic enough to survive every museum poster and childhood obsession that followed. Rex had long existed as a personal name and title before the dinosaur, so T. rex is an association, not its origin. Still, the connection reveals why three letters can feel enormous. The name is compact, declarative, and almost impossible to whisper once a skeleton fills the room. No child called Rex is promised rule, size, or prehistoric ferocity. The story simply gives the old Latin word a memorable second throne, built not in a palace but from bones assembled in a museum.
How popular is Rex around the world?
In the United States, 2,106 babies were named Rex between 2020 and 2025. In England and Wales, 217 boys named Rex were born in 2025, the 228th most common name among boys that year.
Rex is on the official records of the United States, England and Wales, Scotland, New Zealand, South Australia, Canada, Spain and Brazil.
United States
1 in 10,000
In the United States, 2,106 babies were named Rex between 2020 and 2025.
Shape drawn from US Social Security baby-name records. Rex peaked in the 1930s and the 2020s in nearly equal measure.
Births with a Social Security record. Source: U.S. Social Security Administration
England and Wales
1 in 2,700
In England and Wales, 217 boys named Rex were born in 2025, the 228th most common name among boys that year.
share of that year’s name registrations
Birth registrations in England and Wales (not the whole UK); exact spellings are counted separately, and any spelling under 3 in a year is withheld at source. Source: Office for National Statistics, baby names in England and Wales
Scotland
1 in 5,100
In Scotland, 9 boys named Rex were registered in 2024, the 382nd most common name among boys that year.
share of that year’s name registrations
Births registered in Scotland; different spellings count separately but accents are merged at source, and any spelling under 3 in total is suppressed. Source: National Records of Scotland, babies' first names
New Zealand
1 in 5,200
In New Zealand, 11 boys named Rex were registered in 2025.
share of that year’s name registrations
First given names from New Zealand birth registrations, grouped by registration year; any name under 10 in a year is excluded at source. Shares divide by Stats NZ’s count of births registered to mothers living in New Zealand, under 1% below the registry’s own count. Source: Department of Internal Affairs (New Zealand), baby name popularity over time
South Australia
1 in 9,2002017
In South Australia, 2 boys were registered as Rex in 2017.
share of that year’s name registrations
Births registered in South Australia (not all of Australia) by first name and year of registration, 1944–2017, from the state’s Births, Deaths and Marriages registry, which publishes every name down to a single birth in capitals; a spelling its export repeats inside a year is counted once, and from 2018 only a top 100 is published, so the series ends at 2017. Source: Consumer and Business Services (South Australia), popular baby names
Canada
1 in 15,000
In Canada, 25 boys named Rex were born in 2024, ranked 1,011th among boys that year.
share of that year’s name registrations
First given names from provincial and territorial vital statistics across Canada; any name-sex-year under 5 is excluded at source, and small Quebec counts carry a randomized adjustment made at source. Shares divide by Statistics Canada’s count of live births for the year; the 2024 count is preliminary. Source: Statistics Canada, first names at birth (table 17-10-0147-01)
Spain
1 in 1.1M
In Spain, 41 residents are named Rex, ranked 17,205th among men, with a mean age of 47.4 years.
Residents of Spain on 1 January 2025. Spain publishes how old a name’s living bearers are, not a birth series, so there is no year chart. Source: INE (Spain), Censo de Población anual, 1 January 2025
Austria
last on record 2022
Rex is not on the 2025 record for Austria, which publishes every first name down to a single birth, so the name was not given there that year.
The count never rose above 1 in a year, too few to chart.
Live births in Austria by year of birth, 1984–2025, from Statistik Austria’s first-name statistics; spellings that differ only by special characters are counted together (umlauts stay apart), every name down to a single birth is published, and the count covers babies with Austrian citizenship only until 2009, every baby from 2010, and from 2015 also births abroad to mothers living in Austria. Shares divide by Statistik Austria’s count of live births from 2010, and before that by the file’s own total for the year. Source: Statistik Austria - data.statistik.gv.at (OGDEXT_VORNAMEN_1, updated 2026-07-09)
Brazil
At the 2022 census, 27 people in Brazil were named Rex, ranked 101,516th, with a median age of 51.
People alive and resident in Brazil at the 2022 census, a living-population count, not births; names under 20 are withheld at source. Source: IBGE, Censo Demográfico 2022
Ireland
last on record 2024
Rex is not on the 2025 record for Ireland, where names under 3 in a year are withheld at source.
The count never rose above 6 in a year, too few to chart.
Exact registered spellings from Irish vital statistics; any name under 3 in a year is withheld at source, and accented spellings (fadas) are recorded reliably only from 2018. Source: Central Statistics Office (Ireland), Irish babies' names
Montevideo City
last on record 1961
Rex is not on the 2011 record for Montevideo, whose registry withholds nothing, so the spelling was not given there that year.
The count never rose above 1 in a year, too few to chart.
Births in the department of Montevideo (not all of Uruguay) by first name and year of birth, 1940–2011, from the city’s civil registry, which writes names in capitals, almost always without accents; counted as spelling groups (accent and punctuation variants merged), nothing is withheld at source, and 2012 is excluded as a partial year. Source: Servicio de Registro Civil, Intendencia de Montevideo, Partidas de Registro Civil de Montevideo (Licencia de Datos Abiertos - Uruguay); 2012 dropped as partial
Not on the record in Mexico City, Argentina, Puerto Rico and Poland: those registries withhold small counts, so rare uses may sit below their floors.
Not on the Chile record: nametree keeps spellings that reached 5 registrations in some year, so rarer uses are not shown. Not on the France record: nametree keeps spellings that reached 20 births in some year, so rarer uses are not shown. Not on Norway’s list: Statistics Norway lists only first names carried by 200 or more living people, so rarer names are not shown.
Keep exploring
The Rex deep dive
Whether you’re naming a baby or exploring your own name’s history, this is a personal letter, not a list: where Rex truly comes from, how it traveled, and what a century of records reveals. If you have grown a tree on nametree, it also considers how Rex fits with your family’s names and surname.
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