Don Messick
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.
Known for
Scooby Doo, Where Are You! 
The Flintstones 
The Last Unicorn 
The Jetsons 
Charlotte's Web 
The Smurfs 
The Hobbit 
Scooby-Doo and the Ghoul School 
Jetsons: The Movie 
Scooby-Doo and the Reluctant Werewolf 
Scooby-Doo Meets the Boo Brothers 
The Return of the King 
Jack Frost 
Rudolph's Shiny New Year 
Dastardly and Muttley in Their Flying Machines 
The 13 Ghosts of Scooby-Doo 
The Jetsons Meet the Flintstones 
Rudolph and Frosty's Christmas in July 
Tiny Toon Adventures: How I Spent My Vacation 
Nestor, the Long-Eared Christmas Donkey 
Scooby-Doo in Arabian Nights 
A Flintstones Christmas Carol 
Scooby Goes Hollywood 
Pufnstuf 
Hey There, It's Yogi Bear 
A Flintstone Christmas 
The First Christmas: The Story of the First Christmas Snow 
The Good, the Bad, and Huckleberry Hound 
Rockin' with Judy Jetson 
Yogi's Great Escape 
The War Within 
Yogi & the Invasion of the Space Bears 
The Flintstones: Wind-Up Wilma 
Scooby Doo & the Robots