Cillian
- Pronunciation
- [Ci-lli-an]
- Gender
- Male
- Meaning
- Battle
- Origin
- Irish
About the Name Cillian
Cillian is a traditional Irish masculine name derived from the Old Irish Cillín or Ceallach, with the core element often linked to concepts of battle or strife — a meaning deeply at home in the heroic tradition of early Irish culture. Early Irish saints bore forms of this name, and it appears in medieval ecclesiastical records across Munster and Connacht, cementing its place in the fabric of Irish Christian heritage. The pronunciation — roughly "KIL-ee-an" — surprises many English speakers who encounter the spelling for the first time, but that slight mystery has become part of the name's modern allure rather than a barrier to adoption.
Cillian's rise in the United States is a textbook example of how globally connected media culture now shapes American baby-naming. Irish names with strong sonic appeal have found receptive American audiences before, but Cillian's recent momentum is particularly striking, driven by widespread cultural fascination with Irish identity and a broader appetite for names that feel both ancient and genuinely uncommon on a US playground. Variants Kilian and Killian offer anglicized routes to essentially the same name, with Killian having held its own independent presence in American naming for years.
Cillian first entered the US Social Security top-1000 in 2020, and its growth has been remarkably swift — it peaked in 2024 at #463, its all-time best rank, with 668 births that year alone. From 737th place in 2022 to 463rd in 2024, the trajectory is sharply upward across a total of 2,064 top-1000 births tracked so far. Recorded variants include Kilian and Killian.
Source: U.S. Social Security Administration name data, 1880–2024 (methodology). By Marvin Tang.
Quick Facts About Cillian
US Popularity History (2020–2025)
Annual US births named Cillian by gender, from US Social Security Administration records. Peak year: 2024 with 668 boys named Cillian (boy rank #463 that year).
Where it stands today: in 2025, ranked #507 for boys (595 US births). That's 44 places below its 2024 peak.
Source: US Social Security Administration. Limitations: US birth-certificate data only; names appearing fewer than 5 times in a given year are suppressed for privacy; spelling variants are counted separately. For names that ranked outside the US top 100 before year 2000, only the years they reached the top 100 are shown — the chart may have gaps for less-popular historical names.
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Where in the US Is Cillian Most Popular?
Average boy-name rank within each state across 2016–2025 SSA records. A lower number means the name appears closer to the top of that state's boys-name rankings — a per-capita measure that isn't biased toward large states. For Cillian the strongest states are New Hampshire, Massachusetts, Connecticut.
Strongest boys-name states
| # | State | Avg rank | Births |
|---|---|---|---|
| 1 | New Hampshire | #239 | 15 |
| 2 | Massachusetts | #354 | 141 |
| 3 | Connecticut | #413 | 40 |
| 4 | Oregon | #476 | 30 |
| 5 | Minnesota | #509 | 31 |
| 6 | New York | #531 | 247 |
| 7 | New Jersey | #569 | 89 |
| 8 | Colorado | #582 | 58 |
| 9 | Maryland | #590 | 50 |
| 10 | Pennsylvania | #601 | 129 |
Weakest boys-name states
| # | State | Avg rank | Births |
|---|---|---|---|
| 1 | Michigan | #786 | 36 |
| 2 | Florida | #775 | 61 |
| 3 | Tennessee | #766 | 27 |
| 4 | California | #758 | 185 |
| 5 | Indiana | #741 | 39 |
| 6 | Missouri | #724 | 22 |
| 7 | Arizona | #717 | 41 |
| 8 | Ohio | #675 | 116 |
| 9 | North Carolina | #671 | 73 |
| 10 | Virginia | #634 | 77 |
Source: SSA state-level baby-name dataset 2016–2025. States with fewer than 3 years of data for Cillian in this window are excluded. Births < 5 in a given state-year are suppressed by SSA for privacy.
Variant Forms
Looking for names like Cillian?
A dedicated page with 60+ related names — spelling variants, rhymes, alliterations, same-origin matches, and shared meaning concepts — lives at its own URL so each kind of similarity gets a deeper treatment than fits here.
Compare Cillian to Other Popular Names
Side-by-side popularity charts and crossover years for Cillian against today's most popular boys-name peers (top 8 by US births in the last 10 years of SSA records).