Scooby-Doo, Where Are You! made its CBS network debut on Saturday, September 13, 1969 with its first episode, "What a Night for a Knight." 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.[14] Scooby's speech patterns closely resembled an earlier cartoon dog, Astro from The Jetsons (1962–63), also voiced by Messick.[2] Seventeen episodes of Scooby-Doo were produced in 1969. The series theme song was written by David Mook and Ben Raleigh, and performed by Larry Marks and Paul Costello.