Just wanted to start a list of famous martial artists with bodybuilding/strength sports backgrounds and bodybuilders/strength athletes with martial arts backgrounds.
Bolo Yeun- Studied a variety of martial arts and noted for his b-movie appearances. He is also a Hong Kong bodybuilding champ and a Chinese Powerlifting Champ.
Jean-Claude Van Damme- Shotokan Karate champ and pro bodybuilder. Noted for his action movies.
Bas Rutten- Famous Dutch MMA fighter. He was one of the best javelin and discus throwers in his county during his high school career.
Ken Yasuda- Bodybuilder with an extensive martial arts background. He trains many MMA fighters and is a founder of his own style of martial arts.
Colin Osborne- Australian Bodybuilder and Powerlifter who was an amateur boxing champ as a child. Later he became an enthusiastic karate instructor and practicioner.
Simon Robinson- British bodybuilder who was into tae kwon do and even competed for a spot on the Olympic Team.
Sylvio Simac- Did ShotPut as a child and won several British Tae Kwon Do titles. He later got into Bodybuilding, acting , and modeling.
Julien Greaux- Started Karate as a child and is now into MMA style training. He works as a fitness model and I am not sure if he has enter any bodybuilding shows.
Fred George- Bodybuilder who has fought MMA twice and studies under Erik Paulson. Personal trainer for Kevin Randleman a while back.
Jamie Hale- Competed in bodybuilding and Oly lifting and of course is now very into MMA.
Billy Rush- I believe he was into bodybuilding before getting into MMA.
All I have for now. Sorry the description were so brief. Hope everyone can add something.