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Cillian

♂ Boy

Pronounced KIL-ee-an /ˈkɪliən/High

Meaning: From Old Irish Cellach or Cillín, derived from cill meaning 'church' with a diminutive suffix, meaning 'little church' or 'associated with the church'; also linked to ceallach meaning 'bright-headed'Medium

In 30 seconds: Cillian is a classic Irish name steeped in early Christian history. Borne by an Irish missionary saint and now a globally recognized name thanks to actor Cillian Murphy, it blends Celtic heritage with modern cool.
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Origin HighIrish Gaelic
MeaningFrom Old Irish Cellach or Cillín, derived from cill meaning 'church' with a diminutive suffix, meaning 'little church' or 'associated with the church'; also linked to ceallach meaning 'bright-headed'
U.S. rank (2025)#507 ↘ Falling
2025 U.S. births595 boys (0.03% of U.S. boys)
Peak year2024
Total births (all-time)≈ 4,081

Popularity in the U.S. · SSA data

peak 202419952025

U.S. births per year (Social Security Administration, 1880–present). Pink marker = peak year.

History & Origin

Cillian derives from the Old Irish cill meaning 'church,' reflecting the deep influence of early Christianity on Irish naming. The 7th-century missionary Cillian traveled from Ireland to Franconia (now Germany), where he was martyred and later canonized. The name was popular in medieval Ireland.

After centuries of primarily Irish use, Cillian gained international recognition through the success of actor Cillian Murphy, star of Peaky Blinders and Oppenheimer. The name entered British and American charts in the 2010s and 2020s, pronounced KIL-ee-an in its authentic Irish form — a point of fascination for non-Irish speakers.

Did you know? Saint Killian (Cillian) of Würzburg was an Irish missionary who evangelized the Franks in the 7th century and was martyred in 689 AD. His feast day is still celebrated in Würzburg, Germany, where he is the patron saint.
Overall data confidence 80%
Behind the Name — Cillian — etymology and Irish usageU.S. Social Security Administration — popularity data

Variations

KillianKilianKillien

Nicknames

CillKilly

Famous Bearers

  • ★Saint Kilian of Würzburg (c. 640–689)
    Irish missionary to Franconia, martyred and canonized; patron saint of Würzburg.
  • ★Cillian Murphy (1976–present)
    Irish actor known for Peaky Blinders and the film Oppenheimer.

If you like Cillian…

Killian— the anglicized spelling of exactly the same Irish name
Declan— another strong Irish saint name with the same three-syllable Celtic feel
Finnian— Irish saint name sharing the same early-Christian Irish heritage
Ronan— popular Irish boys' name with the same crisp Celtic character

Frequently Asked

What does the name Cillian mean?

Cillian comes from Old Irish cill meaning 'church,' with a diminutive suffix — meaning 'little church' or 'associated with the church.' It may also derive from ceallach meaning 'bright-headed.'

How do you pronounce Cillian?

It is said KIL-ee-an — three syllables. In Irish, the C is pronounced like K.

Is Cillian a boy or girl name?

Cillian is used exclusively as a boys' name.

How popular is Cillian?

Cillian has risen rapidly in English-speaking countries since 2020, largely due to the fame of actor Cillian Murphy.