Brennan is a moderately popular boys' name in United States, ranking #318 in 2012 with 1,011 recorded births. The name reached its all-time peak in 2009 with 1,464 births ranking #242. Since 1996, the popularity has increased by 13.0%. In 2012, approximately 1 in every 1,876 boys born was named Brennan. STABLE Recent data shows the name is currently stable.