Muttley is a dog from the animated series The Mumbly Cartoon Show (1976) and the Laff-a-Lympics (1977) by Hanna-Barbera.
Mumbly was a police dog. Now, he is the captain of the Really Rottens and sidekick of Dread Baron.
Creation
Mumbly is confused with Muttley the sideckick of Dick Dastardly from Wacky Races (1968) and Dastardly and Muttley in Their Flying Machines (1969), both were voiced Don Messick, however, both characters are prototyped by the dog Mugger from the film Hey There, It’s Yogi Bear (1964), also voiced by Messick.
Muttley and Dick Dastardly are replaced by Mumbly and Dread Baron in the animated series Laff-a-Lympics (1977) and the film Yogi Bear and the Magical Flight of the Spruce Goose (1987). One possible explanation is that since Wacky Races was co-produced with Heatter-Quigley Productions, perhaps Hanna-Barbera did not have the rights to Muttley and Dick Dastardly.
Interestingly, around the same time as the film, the duo Muttley and Dick Dastardly appears in the animated series Yogi’s Treasure Hunt (1985-1988).
In Laff-A-Lympics #13, (March 1979) published by Marvel Comics, written by Mark Evanier and illustrated by Jack Manning, Scott Shaw and Dan Spiegle, reveals that Dick and Dread are twin brothers.
Apparently, that issue was resolved and Muttley and Dick were never replaced in other works.