Jay Dee "B.J." Penn (born December 13, 1978) is an American professional mixed martial artist and Brazilian Jiu-Jitsu practitioner. Penn debuted and competed in the Ultimate Fighting Championship (UFC), as well as in K-1. Prior to fighting for the UFC, he became the first American Gold medalist of the World Jiu-Jitsu Championship. In mixed martial arts, Penn has competed in the Featherweight, Lightweight, Welterweight, Middleweight and Heavyweight divisions. As a former UFC Lightweight Champion and UFC Welterweight Champion, he is only the second fighter in UFC history to win titles in multiple weight classes. Penn was also a Finalist in the UFC 41 Lightweight Tournament, due to an eventual draw opposite Caol Uno in the tournament finale. Through his tenures as champion, Penn unified the UFC Lightweight Championship (against Sean Sherk) to become the division's first Undisputed Champion; as well as broke the UFC all-time lightweight title defense record. Penn is to be inducted into the UFC Hall of Fame following his retirement from the sport.During his reign, Penn holds the distinction of being undefeated as a Lightweight for over eight years, spanning a nine-fight unbeaten streak in the division. As a three-time world champion, Penn secured his first title in K-1, submitting (Pride Champion and Grand Prix Winner) Takanori Gomi for the Rumble on the Rock Lightweight Championship. He promptly moved up into the Welterweight division, submitting long-reigning then-champion Matt Hughes to capture the UFC Welterweight Championship, which was eventually relinquished due to a contract dispute. Penn later returned to the Lightweight division to submit both Jens Pulver and Joe Stevenson en route to claiming the vacant UFC Lightweight Championship. He made a record, three-subsequent title defenses, defeating challengers Sean Sherk, Kenny Florian, and Diego Sanchez.UFC President, Dana White credits Penn as the man who brought the lower weight divisions into the mainstream of mixed martial arts; claiming Penn to be "the first crossover pay-per-view star for the Ultimate Fighting Championship's lighter weight divisions", as well as that "[through his] accomplishments, B.J. Penn built the 155 pound division". Credited as the greatest Lightweight combatant in mixed martial arts history, Penn's domination of the division, as well as his performances in higher weight classes have him regarded as one of the greatest fighters in the history of the sport.