William Biggers has died at the age of 85. The co-creator of "Underdog," died unexpectedly in his Plymouth, Massachusetts home on Sunday, family friend Derek Tague told the AP.

Biggers, who preferred to by the nickname "Buck," was a writer for publications like TV Guide, Family Circle and Reader's Digest, and produced several novels, including "The Man Inside" and "Hold Back the Tide."

Yet William Biggers's most famous undertaking was of course the Saturday morning cartoon "Underdog" which ran for 124 episodes on NBC, between 1964 until 1973.

The catch phrase for Biggers's cartoon talking dog, "there's no need to fear. Underdog is here!" became engrained forever in the pop culture consciousness.

The Biggers cartoon "Underdog" is a about a talking dog named Shoeshine Boy (voiced to hilarious perfection by Wally Cox) who transforms into Underdog the heroic canine superhero, whenever gangster Riff Raff or mad scientist Simon Bar Sinister threaten his true love, Sweet Polly Purebred.

After growing up in Georgia, Biggers went to work for the New York City advertising firm DFS.

It was there that he received the assignment that would ensure the William Biggers name never dies, at least for cartoon fans.

Executives from DFS's biggest client, General Mills asked Biggers to create Saturday morning cartoons to promote the company's breakfast cereals. Although Biggers created other cartoons, "Underdog" was of course the runaway success.

And Biggers's cartoon dog is as popular as ever. There is an "Underdog" float in the Macy's Day Parade. There was even a live action "Underdog" movie in 2007, starring Jason Lee, Peter Dinklage and Amy Adams.

Biggers' wife of almost 40 years, Grace, died in 1989. He is survived by his daughter, Victoria Biggers, his son, W. Watts Biggers, Jr., and longtime companion Nancy Purbeck.

Funeral arrangements for Biggers will remain private. A memorial service is planned for a later time.

And although those who knew William Biggers and know his work are mourning the loss of an undeniably creative mind, the continued popularity of "Underdog" should ensure that his legacy never dies, thanks to a certain four-legged superhero.