Brennan is a moderately popular boys' name in United States, ranking #263 in 2008 with 1,316 recorded births. The name reached its all-time peak in 2009 with 1,464 births ranking #242. Since 1996, the popularity has increased by 47.0%. In 2008, approximately 1 in every 1,550 boys born was named Brennan. STABLE Recent data shows the name is currently stable.