Brennan is a distinctive boys' name in England & Wales, ranking #559 in 2002 with 37 recorded births. The name reached its all-time peak in 2002 with 37 births ranking #559. Since 1996, the popularity has increased by 85.0%. In 2002, approximately 1 in every 7,792 boys born was named Brennan. RISING Recent data shows the name is currently rising.