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, passed away at 54.

Michael was the gentlest of souls – an exemplar of decency, integrity and kindness

He died at Cedars-Sinai Medical Centre in Los Angeles, where he was being treated for a heart attack, said his fiancée, reality TV personality Reverend Omarosa Manigault, in a statement.

The muscular, 6ft 4in 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.”

“He was a great man with a huge heart and it was an honour and a privilege to represent him,” said his manager, Dan Spilo.

Duncan had a handful of minor roles before The Green Mile brought him an Academy Award nomination for best supporting actor.

“Michael was the gentlest of souls – an exemplar of decency, integrity and kindness,” Frank Darabont, the film’s director, said in a statement. “The sadness I feel is inexpressible.”

The 1999 film, based on the Stephen King novel of the same name, starred Tom Hanks as a corrections officer at a peni­tentiary in the 1930s.

Duncan played John Coffey, a convicted murderer with a surprisingly gentle demeanour and extra­ordinary healing powers.

Duncan’s performance caught on with critics and moviegoers and he quickly became a favourite in Hollywood, appearing in several films a year.

He owed some of his good fortune to Bruce Willis, who recommended Duncan for The Green Mile after the two appeared together in Armageddon.

Duncan would work with Willis again in Breakfast of Champions, The Whole Nine Yards and Sin City.

His industrial-sized build was suited for everything from superhero films (Daredevil) to comedy (Talledega Nights, School for Scoundrels).

His baritone voice alone was good enough for several animated movies, including Kung Fu Panda, Delgo and Brother Bear.

Among Duncan’s television credits are The Apprentice, The Finder, Two and a Half Men and The Suite Life of Zack and Cody.

Born in Chicago in 1957, Duncan was raised by a single mother whose resistance to his playing football led to his deciding he wanted to become an actor.

But when his mother became ill, he dropped out of college and worked as a ditch digger and bouncer to support her.

By his mid-20s, he was in Los Angeles, where he looked for acting parts and became a bodyguard for Will Smith, Jamie Foxx and other stars.

The murder of rapper Notorious B.I.G., for whom Duncan had been hired to protect before switching assignments, led him to quit his job and pursue acting full-time.

Early film and television credits, when he was usually cast as a bodyguard or bouncer, included Bulworth, A Night at the Roxbury and The Players Club.

Last, Duncan had appeared in a video for Peta, the animal rights organisation, 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.”

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