Jim Backus made pomposity musical. He knew how to stretch a vowel until self-importance became audible, how to let a sentence swell with confidence, and how to make a character’s certainty funnier than the mistake that certainty concealed. Long before Thurston Howell III or Mr. Magoo fixed his voice in popular memory, Backus had been developing those effects in radio.

Born in Cleveland in 1913, Backus trained for the stage in New York and entered broadcasting during the years when radio was one of the best schools an actor could have. Microphone work punished vague choices. With no costume or facial expression to complete a joke, a performer had to build social class, temperament and comic rhythm into the sound itself. Backus proved particularly good at men who thought highly of themselves.

On The Alan Young Show he played Hubert Updike III, a wealthy, affected character whose grand manner anticipated some of Backus’s later work. On The Mel Blanc Show he played another self-satisfied figure, Hartley Benson. These were not simply repetitions of one voice. Backus understood the comic mechanics of privilege: the character must never suspect that the audience is laughing at him. The confidence has to survive every humiliation.

That principle found its purest expression in Mr. Magoo. The nearsighted cartoon character charged through a world he continually misread while remaining serenely convinced that everyone else was confused. Backus supplied the bluster but also the warmth that kept Magoo from becoming merely obnoxious. He later said that elements of the voice and temperament drew on his father, whose own cheerful confusion about names and details had stayed with him.

Film gave Backus opportunities to work against the comic voice audiences expected. In Rebel Without a Cause he played the ineffectual father of James Dean’s character, a role whose weakness is painful rather than ridiculous. He also appeared in It’s a Mad, Mad, Mad, Mad World and scores of other films, but television eventually gave him his most widely recognized live-action character.

As Thurston Howell III on Gilligan’s Island, Backus returned to the territory radio had taught him so well: wealth as a vocal condition. Howell could make a deserted island sound like an inconvenience at a country club. The performance is broader than his radio work, but its mechanics are the same. The voice announces who the man believes himself to be before the script has to explain anything.

Backus continued working across radio, records, film, television and animation for decades. He died in 1989 at 76 after years of illness. His career is often remembered through three characters—Magoo, Howell and the father in Rebel Without a Cause—but radio reveals the craft connecting them. He learned how much biography a voice could carry.