Michael Clarke Duncan, who rose from working as a ditch digger to employ his booming bass voice and immense physical presence in many movie roles, most notably a tragic prisoner with a healing touch in the 1999 film “The Green Mile,” died on Monday in Los Angeles. He was 54.

His fiancée, the Rev. Omarosa Manigault, said the cause was complications of a heart attack he had on July 13, his publicist, Joy Fehily, said.

Mr. Duncan was nominated for both an Academy Award and a Golden Globe for his supporting role in “The Green Mile,” in which he played John Coffey, a mysterious stranger convicted of the rape and murder of two little girls in Louisiana in 1935. Janet Maslin, writing in The New York Times, referred to the “peculiar innocence” with which Mr. Duncan, who was 6-foot-5, imbued the character.