James Gilmore Backus (February 25, 1913—July 3, 1989) was a radio, television, film actor, character actor, and voice actor. Among his most famous roles are the voice of Mr. Magoo, the rich Hubert Updike, III, of the Alan Young radio show, Joan Davis' husband (a domestic court judge) on TV's I Married Joan, James Dean's father in Rebel Without a Cause, and Thurston Howell, III, on the 1960s hit sitcom Gilligan's Island. He also starred in his own show of one season, The Jim Backus Show, also known as Hot off the Wire.

Jim Backus was one of the few actors to do it all: radio, Broadway, movies, television and cartoons. After attending prep school in his native Cleveland, Backus enrolled at the American Academy of Dramatic Art, to ply his trade. While waiting for parts, he did radio and became friends with such future notables as Garson Kanin and Keenan Wynn. Backus stuck it out and soon was doing motion pictures in addition to radio. He was typecast in roles as "rich types" but broke the mold when he portrayed James Dean (I)'s father in the classic Rebel Without a Cause (1955). With his career in full swing, Backus also tackled two roles that he would be best known for, Mr. Magoo in cartoons and Thurston Howell III, in "Gilligan's Island" (1964). After the show's run ended, he continued doing guest spots on television and movies, before passing away on July 3, 1989.