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.
Scrappy-Doo
Scrappy has a contradicted origin. Originally as shown in the introduction of the series, Scrappy only met his Uncle Scooby as a puppy. However, the December 1980 episode of "Scooby-Doo and Scrappy-Doo" ("Scrappy's Birthday") depicts Scrappy-Doo's birth with both Scooby and Shaggy in attendance. Born at St. Bernard's Hospital to Scooby-Doo's sister Ruby-Doo on December 20, 1980, Scrappy idolizes his uncle Scooby and would often assist Scooby and his friends in solving mysteries (Scrappy saves Scooby several times from monsters when they were looking for the rest of the gang). With a highly energetic and brave personality, despite his small size, Scrappy was the exact opposite of his uncle; Scrappy would usually insist on trying to directly fight the various monsters Scooby and his associates encountered and generally have to be dragged away by Scooby. Related to this, one of Scrappy's catchphrases was, "Lemme at 'em! Lemme at 'em! I'll splat 'em! I'll rock 'em and sock 'em!" Another of Scrappy-Doo's catchphrases is, "Ta dadada ta daaa! Puppy power!". He is also quite strong, capable of smashing down solid rock walls and carrying both Scooby and Shaggy over his head seemingly without effort. The character was created by Joseph Barbera and developed by writer Mark Evanier, who has acknowledged that Scrappy's personality was largely based on that of the "Looney Tunes" character Henery Hawk.