A family friend told the AP that Biggers, who went by "Buck," died unexpectedly at his home in Plymouth, Mass.
Born in Georgia, Biggers was working at a New York City advertising firm when he was assigned to create cartoon characters to promote breakfast cereals for the company's biggest client, General Mills. Among his ideas was Underdog, which debuted on NBC in 1964 and featured a canine superhero who was voiced by comedian Wally Cox. In the cartoons, Underdog often battled villains when coming to the rescue of his girlfriend, Sweet Polly Purebred.
Biggers later became the vice president of promotion and creative services at NBC. He also wrote for publications such as Reader's Digest, TV Guide and Family Circle, and published several novels.
In 2007, Underdog was made into a live-action feature film.
Biggers' wife, Grace, died in 1989. He is survived by a daughter, Victoria Biggers; a son, W. Watts Biggers, Jr.; and longtime companion Nancy Purbeck, the AP reports.