After seeing Mr. Harris’s ideas in 1959, Chet Stover, who was creative director on the Trix account, wrote a memo to the company that said, “In a business where the only thing we have to sell are ideas, it is of first importance the credit is given where credit belongs — and Joe gets all the credit for this one.”

Mr. Harris joined Mr. Stover; W. Watts Biggers, an account manager at Dancer; and Treadwell Covington, who worked at a direct-mail agency, to form Total TeleVision, a company that would make Saturday morning cartoons to compete for General Mills’s business with cartoons by Jay Ward and Bill Scott, who created a show centering on the characters Rocky & Bullwinkle.

Mr. Stover and Mr. Biggers were the main writers; Mr. Covington handled audio recording; Mr. Harris drew storyboards and designed characters like King Leonardo, Klondike Kat and Tennessee Tuxedo.

The best known of these characters was Underdog, who was transformed from a canine version of a shoeshiner into a superhero, usually when the reporter Sweet Polly Purebred was threatened by villains, including the evil scientist Simon Bar Sinister and the natty wolf gangster Riff Raff. Mr. Harris drew Underdog as an unlikely hero, a noodle-armed dog engulfed in a baggy red suit and blue cape.