Jose Canseco
Former MLB baseball player Jose Canesco was known for his skills, and later those were overshadowed by his admitting to user performance enhancing drugs. After he retired from baseball, he began competing in mixed martial arts as well as boxing.
Joe Rogan
Comedian, UFC broadcaster, and podcast star Joe Rogan is known for his involvement with MMA and Brazilian jiujitsu. He studied with Eddie Bravo and has earned a brown belt. He has been practicing taekwondo since he was a child and even has a black belt in it. When he was 19, he won the US Open Taekwondo championship.