Popularity trend for the name Cillian in Aotearoa New Zealand, based on Department of Internal Affairs birth registrations.
Cillian reached its highest rank of #302 for boys in 2025. In 2025, 15 babies were registered as Cillian, ranking #302 for boys. Its popularity has stayed fairly steady over the last few years. Cillian is used mainly for boys.
About this data: figures come from Department of Internal Affairs birth registrations for 1954-2025. The DIA only publishes a name for a given year when at least 10 babies were registered with it, so rarer names - and rarer spellings - are missing entirely, and a name can drop out of the record in quieter years. Spelling variants are counted separately, and counts reflect first names as registered.