Dread Baron is the second-in-command of the Really Rottens and the twin brother of Dick Dastardly.
Creation
Dread Baron looks like Dick Dastardly, even his sidekick, Mumbly the dog looks like Dick Dastardly’s sidekick, Muttley, the dogs was voiced by Don Messick, who played a lookalike dog in the film Hey There, It’s Yogi Bear (1964).
Dick Dastardly and Muttley 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 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.