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 on Monday morning at Cedars-Sinai Medical Center in Los Angeles, where he was being treated for a heart attack, said his fiancée, Reverend Omarosa Manigault, in a statement released by publicist Joy Fehily.

The muscular 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."