Duncan 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.
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”.
Duncan had a handful of minor roles before The Green Mile brought him an Academy Award nomination for best supporting actor for his stand-out performance as John Coffey, a wrongfully convicted murderer with extraordinary healing powers.
Born in Chicago in 1957, Duncan became a bodyguard for Will Smith and Jamie Foxx. He turned to acting after the murder of his client rapper Notorious B.I.G.