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

He frequently could be heard on primetime radio programs in the postwar era, including The Jack Benny Program, and he portrayed an exceedingly vain character named Hartley Benson on The Judy Canova Show on the CBS Radio Network, as well as a similar character named Hubert Updike on The Alan Young Show on the NBC Radio Network. He also starred on the short-lived variety program The Jim Backus Show on the ABC Radio Network in 1957 and 1958, when that network changed its name to the American Broadcasting Network (ABN) and tried out a "Live and Lively" format of "Big Time Radio" with orchestras and audiences. Backus costarred in the comedy show I Married Joan from 1952 to 1955, portraying the husband of Joan Davis.