Mugger

Mugger is a dog from the Hanna-Barbera cartoons, he first appeared in the animated film Hey There, It's Yogi Bear! (1964).

According to the Yowp blog, a dog similar to Mugger appears in the Yogi Bear strips in 1965, however, he is brown and not gray like Mugger.

Mugger is a prototype of the characters Muttley (from the series Wacky Races and Dastardly and Muttley in Their Flying Machines) and Mumbly (from The Mumbly Cartoon Show and Laff-A-Lympics). Mugger was also voiced by Don Messick, who would later voice Muttley and Mumbly.