Cillian
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Meaning
probably Old Irish cell, "church", with a diminutive suffix; famously borne by actor Cillian Murphy
The story
Cillian is probably from the Old Irish cell, "church", with a diminutive ending, says Behind the Name, hedge included, and it belonged to a 7th-century Irish saint who evangelized in Franconia and was martyred in Würzburg. The American record barely existed before this century: about 10 boys in the 1990s, about 210 in the 2000s, about 1,200 in the 2010s, and about 2,700 so far this decade. Its famous contemporary bearer is the Irish actor Cillian Murphy, an Academy Award winner, and Behind the Name carries the Anglicized spelling Killian as its own entry, also used in France, with its own separate American record. An Irish saint who died in Bavaria, a probable church at the root, and a C spelling whose American story arrived in force only this century.
How popular is Cillian around the world?
In the United States, 2,668 babies were named Cillian between 2020 and 2025. In Ireland, 271 boys named Cillian were born in 2025, the 9th most common name among boys that year.
Cillian is on the official records of the United States, Ireland, Scotland, England and Wales, New Zealand, Canada, South Australia, Austria, France, Argentina and Spain.
United States
1 in 8,200
In the United States, 2,668 babies were named Cillian between 2020 and 2025.
Shape drawn from US Social Security baby-name records. Cillian peaked in the 2020s.
Births with a Social Security record. Source: U.S. Social Security Administration
Ireland
1 in 200
In Ireland, 271 boys named Cillian were born in 2025, the 9th most common name among boys that year.
share of that year’s name registrations
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. This registry counts each spelling separately; the figures above are for the exact spelling Cillian, and accented spellings are separate names. Source: Central Statistics Office (Ireland), Irish babies' names
Scotland
1 in 740
In Scotland, 62 boys named Cillian were registered in 2024, the 83rd 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
England and Wales
1 in 2,500
In England and Wales, 230 boys named Cillian were born in 2025, the 217th 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
New Zealand
1 in 3,800
In New Zealand, 15 boys named Cillian 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
Canada
1 in 5,600
In Canada, 65 boys named Cillian were born in 2024, the 468th most common name 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)
South Australia
1 in 18,0002017
In South Australia, 1 boy was registered as Cillian in 2017.
The count never rose above 2 in a year, too few to chart.
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
Austria
1 in 38,000
In Austria, 2 boys named Cillian were born in 2025, ranked 1,241st among boys that year, spellings that differ only by special characters counted together.
The count never rose above 4 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)
France
1 in 43,000
In France, about 15 boys named Cillian were born in 2025, ranked 2,059th among boys that year.
share of that year’s births on record
Births in France by year of birth, from INSEE’s fichier des prénoms (1900–2025; Mayotte from 2012); exact spellings count separately (Léo and Leo are different names), any spelling under 3 in a year and sex is withheld at source, every count is rounded to the nearest 5 at source, and nametree keeps the spellings that reached 20 in some year. Shares divide by INSEE’s count of births in France from 1957, and before that by the file’s own total for the year; INSEE says the file is not complete before 1946. Source: Insee, fichier des prénoms (last updated 2026-07-16)
Argentina
1 in 66,000
In Argentina, 10 newborns were given the name Cillian in 2024.
share of that year’s name registrations
Given-name components of births in Argentina 2012–2024; national cells are lower bounds and no sex split is published. Source: RENAPER (Argentina), Dirección Nacional de Población, given names 2012-2024
Spain
1 in 1.2M
In Spain, 36 residents are named Cillian, ranked 18,822nd among men, with a mean age of 8.4 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
Poland
last on record 2017
Cillian is not on the 2025 record for Poland, where names given fewer than 2 times in a year are withheld at source.
The count never rose above 2 in a year, too few to chart.
First names given to children born in Poland by year of birth, 2000–2025, from the PESEL population register (Ministry of Digital Affairs); exact spellings count separately (Łukasz and Lukasz are different names), names given fewer than 5 times in a year were left off the list through 2012 and fewer than 2 times from 2013, and the register also counts children born abroad, so its yearly sums run above Poland’s live births. Shares divide by the register’s own published total for the year, never by births. Source: Ministry of Digital Affairs, PESEL register (dane.gov.pl)
Not on the record in Mexico City and Puerto Rico: 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 Montevideo record for 1940 to 2011: that registry withholds nothing, so this spelling was not given there in those years. Not on Norway’s list: Statistics Norway lists only first names carried by 200 or more living people, so rarer names are not shown.
When you meet Cillian
Most people given the name Cillian in the United States are children or teenagers today. The name belongs to this generation.
Estimated from US Social Security birth registrations and typical lifespans; a rough guide, not a rule.
Keep exploring
The Cillian deep dive
Whether you’re naming a baby or exploring your own name’s history, this is a personal letter, not a list: where Cillian 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 Cillian fits with your family’s names and surname.
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