BJ Penn is a retired American mixed martial artist and Brazilian jiu-jitsu practitioner, widely regarded as one of the greatest fighters in the history of the sport. Born on December 13, 1978, in Kailua, Hawaii, he became the first fighter in UFC history to win titles in two different weight classes: UFC Lightweight and UFC Welterweight. Known for his exceptional grappling skills and striking ability, Penn has competed against many top fighters throughout his career. In addition to his success in the UFC, BJ Penn is a black belt in Brazilian jiu-jitsu, having won the prestigious World Jiu-Jitsu Championship in 2000. He is also known for his fierce rivalry with other fighters, including Georges St-Pierre and Frankie Edgar. After retiring from professional fighting, Penn has remained involved in the sport as a coach and mentor, contributing to the growth of mixed martial arts.