Duncan's death was confirmed by a statement from his fiancée, former Apprentice contestant Omarosa Manigault. Reports say he died Monday morning in a Los Angeles hospital, where he was receiving treatment following a July 13 heart attack.
Among multiple high-profile roles, Duncan portrayed classic Marvel villain the Kingpin in 2003's live-action Daredevil film. The movie was notable for casting an African-American actor as a character traditionally depicted in the comic books as Caucasian, which preceded similar moves including Samuel L. Jackson appearing as Nick Fury in several Marvel Studios films, and British actor Idris Elba playing Heimdall in 2011's Thor.
As a voice actor, Duncan reprised the role of Kingpin in the MTV's 2003 Spider-Man animated series, and voiced roles in the Teen Titans and Static Shock cartoons. He acted in two more comic book-based movies, as Manute in 2005's Sin City, and the voice of CGI-rendered Kilowog in last year's Green Lantern.
Duncan's breakthrough role was as John Coffey in 1999's The Green Mile, earning him Academy Award and Golden Globe nominations for best supporting actor.