William Watts Biggers, the co-creator of the cartoon "Underdog," about a mild-mannered canine superhero, was 85 when he died unexpectedly in Plymouth, Massachusetts.

Biggers was part of the team that created “Underdog’’ while working for New York City advertising firm Dancer Fitzgerald Sample on an assignment for General Mills to come up with television cartoons to promote its breakfast cereals.

"Humble and lovable" Shoeshine Boy would turn into the heroic Underdog whenever gangster wolf Riff Raff and mad scientist Simon Bar Sinister would threaten his love interest, Sweet Polly Purebred. His famous catchphrase was "no need to fear, Underdog is here."

Underdog began on NBC in 1964 and ran in syndication until 1973. The character remained so popular, however, in 2007 a movie based on the cartoon was released starring “Game of Thrones’’ actor Peter Dinklage.