Legendary and controversial coach Béla Károlyi, who died on Friday, played a key role in transforming USA Gymnastics into an Olympic and international competition powerhouse, turning out superstars like Kerri Strug and Nadia Comăneci.

Bela Karolyi, the legendary and controversial Romanian American gymnastics coach who helped lead Mary Lou Retton, Nadia Comaneci and Kerri Strug to Olympic gold, has died, USA Gymnastics announced. He was 82.

Karolyi and wife Martha trained multiple Olympic gold medalists and world champions in the U.S. and Romania, including Nadia Comaneci and Mary Lou Retton.