© Michael Clarke Duncan / AP Actor Michael Clarke Duncan dead at 54 Sept. 3, 2012, 5:53 PM EST LOS ANGELES (AP) -- Michael Clarke Duncan, the hulking, prolific character actor whose dozens of films included an Oscar-nominated performance as a death row inmate in "The Green Mile" and such other box office hits as "Armageddon," "Planet of the Apes" and "Kung Fu Panda," is dead at age 54. Clarke died Monday morning at Cedars-Sinai Medical Center in Los Angeles, where he was being treated for a heart attack, said his fiancée, reality TV personality Rev. Omarosa Manigault, in a statement released by publicist Joy Fehily. Bing: More on Michael Clarke Duncan The muscular, 6-foot-4 Duncan, a former bodyguard who turned to acting in his 30s, "suffered a myocardial infarction on July 13 and never fully recovered," the statement said. "Manigault is grateful for all of your prayers and asks for privacy at this time. Celebrations of his life, both private and public, will be announced at a later date." In the spring of 2012, Clarke had appeared in a video for PETA, the animal rights organization, in which he spoke of how much better he felt since becoming a vegetarian three years earlier. "I cleared out my refrigerator, about $5,000 worth of meat," he said. "I'm a lot healthier than I was when I was eating meat." .