Muttley, a mixed breed dog, first appeared in Wacky Races in 1968, as the sidekick of a nasty but incompetent and horribly accident-prone villain Dick Dastardly. While Dick was created as the equivalent of Professor Fate from the 1960s movie The Great Race, Muttley mirrored the film’s character of Max Meen. Dick and Muttley were paired together in various later Hanna-Barbera series as bumbling villains. Muttley’s birthday is April 16th, as shown in the Dastardly and Muttley in their Flying Machines episode “Sappy Birthday.”

Muttley does not really talk; his main examples of speech are his trademark snicker – a wheezing, asthmatic laugh (usually made at Dick’s expense) – and a mushy, sotto voce grumble against an unsympathetic or harsh Dick (usually along the lines of “Sassafrassarassum Rick Rastardly!”). Don Messick had used Muttley’s distinctive laugh for the character of Griswold in an episode of Top Cat as well as for another Hanna-Barbera canine, Precious Pupp, several years earlier. He also repurposed it for Alexandra Cabot’s cat Sebastian on Josie and the Pussycats in 1970.

Muttley wore only a collar in Wacky Races, but in Dastardly and Muttley in their Flying Machines he donned a World War I style aviator’s cap and scarf, and served as a flying ace along with Dastardly and two other pilots as members of the “Vulture Squadron.” In this spinoff, he also sported many medals, of which he was particularly fond, and constantly demanded new ones from Dastardly for following his commands. Similarly, Dastardly frequently ripped medals off Muttley’s chest as punishment for his incompetence. When he received a new medal, Muttley would hug himself happily, jump into the air and float back down like a feather. This gag is almost identical to the behavior of Snuffles, a dog who appeared on the series Quick Draw McGraw in the late 1950s; and Scooby Doo, in the show A Pup Named Scooby Doo, when he received a Scooby Snack.

Also in Dastardly and Muttley in their Flying Machines, Muttley gained the ability to fly for a brief period by spinning his tail like a propeller. This trait often proved useful when he was about to crash. Muttley also enjoyed his own short segment in this series The Magnificent Muttley, where he would engage in Walter Mitty-style fantasies.

Often, when Muttley grumbled on Dastardly and Muttley in their Flying Machines, Dick Dastardly would say “What was THAT?” accompanied by Muttley kissing his hand, to which Dastardly would usually reply “That’s better”.