The co-creator of the cartoon "Underdog" has died.

William Walter Biggers died unexpectedly at his home in Plymouth, Massachusetts on Sunday.

He was 85.

Biggers worked for a New York City Advertising firm when he was asked to create television cartoons to promote general Mills' breakfast cereal

The most famous was "Underdog", which debuted on NBC in 1964.

The canine superhero, voiced by comic actor Wally Cox, battled villians including Simon Bar Sinister and Riff Raff.

He was famous for the phrase "There's no need to fear, Underdog is here."