John Stephenson is an American voice actor who has voiced additional characters throughout the Scooby-Doo franchise. He has also voiced multiple other characters in Hanna-Barbera productions. He was the voice of Mr. Peevly on Help, It's the Hair Bear Bunch, Luke and Blubber Bear on Wacky Races, Doggie Daddy, Fancy-Fancy on Top Cat, Mr. Finkerton on Inch High, Private Eye, Chief Wiggins on Dynomutt, Professor X on Pryde of the X-Men, Beef Bonk on Galaxy High School and General Flaggs in G.I. Joe. He also voiced four characters on The Transformers: Huffer, Windchanger, Thundercracker and Alpha Trion.
Nonetheless, he is most famous as the voice of Mr. Slate, Fred Flintstone's bad tempered boss in The Flintstones. He has been voicing Mr. Slate from 1960-present.