Donald Earle Messick (September 7, 1926 – October 24, 1997) was an American voice actor, known for his performances in Hanna-Barbera cartoons.[1] His best-remembered voice roles include Scooby-Doo; Bamm-Bamm Rubble and Hoppy in The Flintstones; Astro in The Jetsons; Muttley in Wacky Races and Dastardly and Muttley in Their Flying Machines; Boo-Boo Bear and Ranger Smith in The Yogi Bear Show; Sebastian the Cat in Josie and the Pussycats; Gears, Ratchet, and Scavenger in The Transformers; Papa Smurf and Azrael in The Smurfs; Hamton J. Pig in Tiny Toon Adventures; and Dr. Benton Quest in Jonny Quest.

From Wikipedia.