Scooby-Doo
The first episode of "Scooby-Doo, Where Are You!" "What a Night for a Knight" debuted on the CBS network Saturday, September 13, 1969. The original voice cast featured veteran voice actor Don Messick as Scooby-Doo, radio DJ Casey Kasem (later host of radio's syndicated "American Top 40") as Shaggy, actor Frank Welker (later a veteran voice actor in his own right) as Fred, actress Nicole Jaffe as Velma, and musician Indira Stefanianna Christopherson as Daphne. Scooby's speech patterns closely resembled an earlier cartoon dog, Astro from "The Jetsons" (1962–63), also voiced by Messick. Seventeen episodes of "Scooby-Doo Where are You!" were produced in 1969–70. The series theme song was written by David Mook and Ben Raleigh, and performed by Larry Marks.
Scooby-Doo (character)
Scooby has a speech impediment and tends to pronounce most words as if they begin with an "R"; however, most characters are able to understand him almost perfectly. In most iterations, he keeps his sentences relatively short, usually using charades for anything longer than three or four words. His catchphrase, usually howled at the end of every production, is "Scooby-Dooby-Doo!" or "Rooby-Rooby-Roo". Scooby was voiced by Don Messick through "Arabian Nights" in 1994, after which point Messick quit smoking; quitting smoking changed his voice and prevented him from achieving the same raspy vocal effect (despite Messick's efforts, he suffered a career-ending stroke in 1996 and died in 1997, before any further "Scooby-Doo" productions were made). Messick is also known for providing the voice of the dogs Astro on "The Jetsons" and Muttley (who snickered). The characteristic speech impediments of Scooby and Astro are so similar that Astro's signature phrase, "Ruh-roh!", is popularly and improperly attributed to Scooby (as in "Ruh-roh, Raggy!"); of the two voices, Scooby's had a deeper and throatier timbre than Astro's.