Rising since 1997, #507 for boys today.
Popularity of Cillian since 1995
Babies named Cillian per year in U.S. Social Security records.
Data table (by decade)
| Decade | Boys |
|---|---|
| 1990s | 10 |
| 2000s | 208 |
| 2010s | 1,204 |
| 2020s | 2,662 |
Meaning & origin
Cillian entered the U.S. Social Security data in 1995, and its trajectory has been steadily rising, especially since 1997. By 2025 it reached rank 507 with a 1-in-2,871 birth rate, and its peak year so far is 2024. The name is most concentrated in Alaska, Delaware, and Rhode Island. While its ancient Irish roots link to saints and possibly mean 'little church' or 'warlike', its modern appeal owes much to actor Cillian Murphy. The name balances a distinctive sound with a strong Celtic heritage, appealing to parents seeking something recognizable but not overly common. Its variants, including Killian, add flexibility, while its rising trajectory shows no signs of slowing.
Cillian is an Irish name with debated etymology. It may derive from the Old Irish 'ceallach' ('war, strife') or from 'cell' ('church, monastery'), possibly meaning 'little church'. The name has been borne by several early Irish saints, including Saint Cillian (or Killian), a 7th-century missionary to Franconia. It has seen a resurgence in popularity internationally since the late 20th century, partly due to actor Cillian Murphy.
Where Cillian is most popular
Births per 100,000 boys by state, 2025. The lightest shade means too few recorded births.
“Cillian” around the world
Where Cillian lands in the latest official birth statistics abroad, matched to the U.S. spelling.
France
15
babies in 2024
Ireland
#9
in 2025
New Zealand
15
babies in 2025
Quebec
6
babies in 2025
Sources: INSEE (France) · CSO Ireland (Ireland) · NZ Dept of Internal Affairs (New Zealand) · Retraite Québec (Quebec).
Nicknames & variants
Nicknames: Kil, Cill
Sibling names for Cillian
Names that share Cillian's style, for a brother or sister.
