Cillian is an uncommon boys' name that has climbed to its highest level yet, peaking in 2024.
Cillian is predominantly a boy name. In 2025 it ranked #507 for boy births in the United States (and #1,018 across all names), given to 595 babies. Cillian was first reported in SSA data in 1995 and peaked in 2024 (668 births).
Boys named Cillian per year · hover for count and boys rank · Source: U.S. Social Security Administration, national data 1995–2025 · U.S.+territories from SSA territory files (1998–2025) · SSA publishes a name only in years it was given to at least 5 babies, so a name may have been in use before — or between — the years shown here
Girls named Cillian
Girls named Cillian per year · hover for count and girls rank · Source: U.S. Social Security Administration, national data 1995–2025 · U.S.+territories from SSA territory files (1998–2025) · SSA publishes a name only in years it was given to at least 5 babies, so a name may have been in use before — or between — the years shown here