Billy vs Cillian
Billy and Cilliancompared on official birth-registration statistics and Namewise's recorded data. This page states what each name's record shows — it never picks a winner or scores one name against the other.
Head to head
Ranks are only compared within one published list and one year. Two ranks from different years, from a boys' and a girls' list, or from different registrars are not comparable, so they are not placed side by side.
Northern Ireland · Boys
In 2024, Billy was ranked #256 and Cillian #2 among boys in Northern Ireland.
Republic of Ireland · Boys
In 2025, Billy was ranked #39 and Cillian #9 among boys in Republic of Ireland.
Scotland · Boys
In 2024, Billy was ranked #234 and Cillian #83 among boys in Scotland.
England and Wales · Boys
In 2024, Billy was ranked #127 and Cillian #177 among boys in England and Wales.
Billy and Cillian over time
Billy and Cillian appear together in 3 published lists, across 101 years of shared records. Cillian held the stronger position in more years in 2 of them, Billy in 1.
In none of those lists did their order change and stay changed.
Billy reached its own highest recorded position earlier in 2 of those lists, Cillian in 1. Each position is a place inside its own list, so this compares when they peaked and never how high.
Counted list by list. Two names in the same published list are measured on the same scale in the same year, so those comparisons are real — but positions from different lists are not, so nothing here is combined into an overall standing.
How this pair is related
The relationship kinds these two qualify for, each under its own stated rule. Every one is drawn from a list they both appear in.
- Mirrored each other
Over 29 shared years in England and Wales · Boys, Cillian rose about as far as Billy fell — from #71 and #1104 in 1996 to #127 and #177 in 2024.
- Longest-running competitions
Billy and Cillian were both ranked in Republic of Ireland · Boys for 45 years, from 1970 to 2025, ending at #39 and #9.
- Peaked in the same years
Both reached their highest recorded position in Republic of Ireland · Boys within 2 years — Billy #39 in 2025, Cillian #4 in 2024.
List by list
Republic of Ireland · Boys45 shared years, 1970–2025
Billy held the stronger position in 0 of those years, Cillian in 44.
Highest recorded here: Billy #39 in 2025, Cillian #4 in 2024.
The order between them never changed and held in this list.
Most recent shared year, 2025: Billy #39, Cillian #9.
England and Wales · Boys29 shared years, 1996–2024
Billy held the stronger position in 29 of those years, Cillian in 0.
Highest recorded here: Billy #68 in 1998, Cillian #177 in 2024.
The order between them never changed and held in this list.
Most recent shared year, 2024: Billy #127, Cillian #177.
Northern Ireland · Boys27 shared years, 1998–2024
Billy held the stronger position in 0 of those years, Cillian in 26.
Highest recorded here: Billy #169 in 2015, Cillian #2 in 2024.
The order between them never changed and held in this list.
Most recent shared year, 2024: Billy #256, Cillian #2.
Two names moving past each other in a ranking is a fact about the ranking. Namewise does not claim one name displaced the other, that families chose between them, or that either influenced the other — none of that is in this data.
Side by side
| Field | Billy | Cillian |
|---|---|---|
| Record type | Official statistical record (evidence-only) | Editorially researched profile |
| Gender usage | male | male |
| Meaning | Not yet recorded | Probably from Old Irish 'cell' (church) combined with a diminutive suffix. |
| Origin | Not yet recorded | Irish |
| Pronunciation | Not yet recorded | |
| Syllables | 2 | 2 |
| Common variants / nicknames | Not yet recorded | Not yet recorded |
| Recorded regional usage | AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NZ | GB-ENW, GB-NIR, GB-SCT, IE |
| Most recent popularity observation | Republic of Ireland · Boys #39 (2025) | Republic of Ireland · Boys #9 (2025) |
| Pronunciation clarity (demonstration score) | Not yet recorded | Not yet recorded |
| Spelling simplicity (demonstration score) | 94/100 | 82/100 |
| International familiarity (demonstration score) | 100/100 | 100/100 |
| Data Confidence | medium | medium |
What the data shows
- Cillian has a recorded origin (Irish); Billy does not have one recorded yet.
- Billy and Cillian both have 2 syllables.
- A meaning is recorded for Cillian; Billy doesn't have one written yet.
- Both names have recorded usage in GB-ENW, GB-NIR, GB-SCT, IE.
How each name got here
Billy
Popularity journey
First recorded1970
First recorded at #305 among boys in Republic of Ireland in 1970 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Republic of Ireland · Boys
Highest recorded1970–2025
Highest recorded position: #39 among boys in Republic of Ireland, in 2025 (recorded 1970–2025).
Republic of Ireland · Boys
Most recent2025
Most recently recorded at #44 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys
Cillian
Popularity journey
First recorded1970
First recorded at #305 among boys in Republic of Ireland in 1970 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Republic of Ireland · Boys
Highest recorded1997–2024
Highest recorded position: #2 among boys in Northern Ireland, in 2024 (recorded 1997–2024).
Northern Ireland · Boys
Most recent2025
Most recently recorded at #9 among boys in Republic of Ireland, in 2025.
Republic of Ireland · Boys