Cause of death: natural cause
Charles Edward Durning (February 28, 1923 – December 24, 2012) was an American actor who appeared in over 200 movies, television shows and plays. Durning's best-known films include The Sting (1973), Dog Day Afternoon (1975), The Muppet Movie (1979), True Confessions (1981), Tootsie (1982), Dick Tracy (1990), and O Brother, Where Art Thou? (2000). He was nominated for the Academy Award for Best Supporting Actor for both The Best Little Whorehouse in Texas (1982) and To Be or Not to Be (1983). Prior to his acting career, Durning served in World War II and was decorated for valor in combat.
Source : Wikipedia