Killian vs Theo
Killian and Theocompared 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.
Scotland · Boys
In 2024, Killian was ranked #268 and Theo #4 among boys in Scotland.
Northern Ireland · Boys
In 2024, Killian was ranked #187 and Theo #5 among boys in Northern Ireland.
England and Wales · Boys
In 2024, Killian was ranked #638 and Theo #12 among boys in England and Wales.
Republic of Ireland · Boys
In 2025, Killian was ranked #141 and Theo #21 among boys in Republic of Ireland.
Killian and Theo over time
Killian and Theo appear together in 3 published lists, across 82 years of shared records. Theo held the stronger position in more years in 2 of them, Killian in 1.
The order between them changed and held in one of those lists — a change in that published list, never a claim that one name displaced the other.
Killian reached its own highest recorded position earlier in 2 of those lists, and Theo in none. 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.
- One moved ahead of the other
In 2017, Theo moved ahead of Killian in Republic of Ireland · Boys — #87 and #106 the year before became #106 and #73.
- Longest-running competitions
Killian and Theo were both ranked in Republic of Ireland · Boys for 30 years, from 1988 to 2025, ending at #141 and #21.
- Peaked in the same years
Both reached their highest recorded position in England and Wales · Boys within 2 years — Killian #492 in 2022, Theo #9 in 2022.
List by list
Republic of Ireland · Boys30 shared years, 1988–2025
Killian held the stronger position in 21 of those years, Theo in 9.
Highest recorded here: Killian #55 in 2001, Theo #13 in 2024.
The order changed in 2017: Theo moved ahead. In 2016 they stood at #87 and #106; by 2017 that had become #106 and #73.
Most recent shared year, 2025: Killian #141, Theo #21.
England and Wales · Boys29 shared years, 1996–2024
Killian held the stronger position in 0 of those years, Theo in 29.
Highest recorded here: Killian #492 in 2022, Theo #9 in 2022.
The order between them never changed and held in this list.
Most recent shared year, 2024: Killian #638, Theo #12.
Northern Ireland · Boys23 shared years, 2001–2024
Killian held the stronger position in 4 of those years, Theo in 19.
Highest recorded here: Killian #157 in 2017, Theo #4 in 2022.
The order between them never changed and held in this list.
Most recent shared year, 2024: Killian #187, Theo #5.
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 | Killian | Theo |
|---|---|---|
| Record type | Official statistical record (evidence-only) | Editorially researched profile |
| Gender usage | male | male |
| Meaning | Not yet recorded | Gift of God. |
| Origin | Not yet recorded | Greek, via Theodore/Theodora |
| Pronunciation | Not yet recorded | /ˈθioʊ/ |
| Syllables | 2 | 1 |
| Common variants / nicknames | Not yet recorded | Teddy |
| Recorded regional usage | GB-ENW, GB-NIR, GB-SCT, IE | AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ |
| Most recent popularity observation | Republic of Ireland · Boys #141 (2025) | Republic of Ireland · Boys #21 (2025) |
| Pronunciation clarity (demonstration score) | Not yet recorded | 90/100 |
| Spelling simplicity (demonstration score) | 82/100 | 95/100 |
| International familiarity (demonstration score) | 100/100 | 100/100 |
| Data Confidence | medium | high |
What the data shows
- Theo has a recorded origin (Greek, via Theodore/Theodora); Killian does not have one recorded yet.
- Killian has 2 syllables, compared with 1 for Theo.
- A meaning is recorded for Theo; Killian doesn't have one written yet.
- Both names have recorded usage in GB-ENW, GB-NIR, GB-SCT, IE.
- The available evidence gives Killian a "medium" Data Confidence level and Theo a "high" level — this reflects how complete and corroborated the underlying evidence is, not a judgement of either name.
How each name got here
Killian
Popularity journey
First recorded1964
First recorded at #204 among boys in Republic of Ireland in 1964 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Republic of Ireland · Boys
Highest recorded1964–2025
Highest recorded position: #55 among boys in Republic of Ireland, in 2001 (recorded 1964–2025).
Republic of Ireland · Boys
Most recent2025
Most recently recorded at #141 among boys in Republic of Ireland, in 2025.
Republic of Ireland · Boys
Theo
Popularity journey
First recorded1986
First recorded at #637 among boys in Norway in 1986 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Norway · Boys
Highest recorded2001–2024
Highest recorded position: #4 among boys in Northern Ireland, in 2022 (recorded 2001–2024).
Northern Ireland · Boys
Most recent2025
Most recently recorded at #32 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys