Brennan is a distinctive boys' name in England & Wales, ranking #544 in 2001 with 35 recorded births. The name reached its all-time peak in 2002 with 37 births ranking #559. Since 1996, the popularity has increased by 75.0%. In 2001, approximately 1 in every 8,223 boys born was named Brennan. RISING Recent data shows the name is currently rising.