Brennan is a distinctive girls' name in United States, ranking #9557 in 2025 with 10 recorded births. The name reached its all-time peak in 2007 with 100 births ranking #2039. Since 1996, the popularity has decreased by 83.3%. In 2025, approximately 1 in every 160,727 girls born was named Brennan. FALLING Recent data shows the name is currently falling.