Duncan died in Los Angeles, his fiancée, the reality television star Omarosa Manigault, said in a statement through Duncan's publicist, Joy Fehily.
He suffered a heart attack on July 13 and "never fully recovered," Fehily said. He passed away at Cedars-Sinai Medical Center, she said.
With a commanding screen presence from his deep voice and hulking 6-foot-5 (1.96-metre) frame, Duncan once dug ditches for the gas company in his native Chicago, then moved to Los Angeles to pursue his career as an actor.
He worked as a bodyguard and bouncer and played a few roles of that kind in film and television, before landing a small part in the 1998 movie "Armageddon."
That led to a much larger role in the 1999 prison drama "The Green Mile" with Tom Hanks. Duncan played a death row inmate with magical powers who is put to death for two murders he did not commit.
The role won him a supporting actor Oscar nomination. "Duncan's ... presence is literally and figuratively the biggest thing in the movie," wrote Washington Post critic Desson Howe.
He had roles in 2002 film "The Scorpion King," the 2003 comic book movie "Daredevil" and 2005 release "Sin City." He also did voice work for the 2008 animated film "Kung Fu Panda."
And he starred this year in several episodes of the Fox crime drama "The Finder."
In the 1980s Duncan tried out for the Chicago Bears, and he also played basketball in community college. His affinity for sports included narrating a film about the 2005 World Series champions Chicago White Sox.
Manigault, 38, is best known for her appearances on NBC reality show "The Apprentice," in which she often acted the villain. More recently, she studied Christian theology and became a minister.
"Manigault is grateful for all of your prayers and asks for privacy at this time," Fehily said. (Reuters)
