Together with his wife Martha, he formed Nadia Comaneci, then 14 years old, into an Olympic Games gold medalist in 1976 in Montreal. The Romanian became the first to receive the highest score of 10.0 in an Olympic competition.
Decades later, they were behind, or had a part in, the successes of American world stars and Olympic winners such as Mary Lou Retton and Simone Biles, among others. They made the USA a superpower in the sport.
But the image of Bela, and the couple, came to be tarnished over the more than 30 years in the USA, where they arrived after defecting from the then communist regime in Romania in 1981.
Their coaching regime was extremely tough and debated. Some hated them, others loved them.
When the so-called Nassar scandal erupted in the USA in 2016, they were considered accomplices by many of the victims.
They had contributed to the harsh culture of obedience and discipline that existed in the American gymnastics camp, a culture that had made it possible for team doctor Larry Nassar to subject hundreds of gymnasts to sexual abuse under the guise of treatment.
Nassar was given a de facto life sentence for the abuse.
The Karolyi couple claimed that they had not known what was happening.
