Born in Paris, Ky., Kelly attended the University of Louisville and played football, but eventually turned his attention to karate and other martial arts. In 1971, won the middleweight title at the 1971 Long Beach International Karate Championships and opened his own dojo afterward.
In 2010, Kelly told Salon.com that working on Enter the Dragon, in which he played wisecracking martial artist Williams, was "one of the best experiences in my life. Of his co-star Lee, Kelly said: "Bruce was just incredible, absolutely fantastic. I learned so much from working with him. I probably enjoyed working with Bruce more than anyone else I'd ever worked with in movies because we were both martial artists. And he was a great, great martial artist. It was very good."