Supporting player from the stage and radio who entered film in 1942 but remained best known for his distinctive voices. Usually cast in humorous parts, Backus was most memorable in a rare dramatic performance as James Dean's ineffectual father in "Rebel Without a Cause" (1955). He was the voice of cartoondom's bumbling "Mr. Magoo" and played the pompous millionaire, Thurston Howell III, on the TV cult series, "Gilligan's Island" (1964-67).