In the early years at Kronk, most of his fighters were black. In recent years, his melting pot of boxers included a Ukrainian heavyweight, an Irish middleweight and scores of young men from Eastern Europe, Latin America and the Middle East.
Steward was inducted into the International Boxing Hall of Fame in 1996.
"It brings me great grief and sadness to hear of the passing of one of the best and most respected trainers of this era," De La Hoya said. "I learned a lot from him during our professional relationship and I will be forever grateful for his help during that time. We were also friends and I know I am going to miss him as so many others will, too. He was an important part of our boxing community."
Lewis, a former heavyweight champion, was trained by Steward from 1994 to 2004, a period which included victories over Evander Holyfield and Mike Tyson.
"This has been a very tragic year for the boxing world, but today we've truly lost one of its crown jewels," Lewis wrote on his official website. "Manny always told me I was the best, but the truth is, he was the best and I'm grateful, privileged and honored to be counted among his many historic successes.
"Manny was giving, selfless, compassionate and stern," Lewis said. "I'm proud to have had him in my corner for so many years. ... I'll miss his smile, his frank no-holds-barred truthfulness and our discussions on boxing and life."
Steward also worked Klitschko, the current heavyweight champion, as recently as July when the boxer led 22,000 fans in singing "Happy Birthday," to the beloved trainer.
Klitschko had to train recently without Steward for his fight against Mariusz Wach next month in Germany
"His spirit is always here," Klitschko said. "I can hear his voice in sparring while doing things, whispering in my ear. As the famous saying goes, 'The show must go on,' and that's exactly the case."
Steward also trained actor Wesley Snipes for his role as a boxer in "Undisputed" and appeared briefly with Lewis in "Ocean's Eleven."
Steward worked since 2001 as a boxing analyst for HBO, sharing his rich knowledge of the sport and warm personality with a younger generation of fans.
"Manny was a respected colleague who taught us so much not only about the sweet science but also about friendship and loyalty," HBO Sports President Ken Hershman said. "His energy, enthusiasm and bright smile were a constant presence. Ten bells do not seem enough to mourn his passing."
HBO Sports commentator Jim Lampley — a friend of Steward's since the early 1980s and broadcast partner for more than a decade — said Steward's wisdom and common touch made him special.
"He was the most loyal, generous, positive spirited, broadly accepting man I've ever known," Lampley said. "He had a positive impact on everyone he encountered."
AP Sports Columnist Tim Dahlberg contributed to this report.
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