Killian is a moderately popular boys' name in United States, ranking #418 in 2025 with 770 recorded births. The name reached its all-time peak in 2017 with 1,505 births ranking #248. Since 1996, the popularity has increased by 431.0%. In 2025, approximately 1 in every 2,218 boys born was named Killian. FALLING Recent data shows the name is currently falling.