Scooby Doo first aired on CBS and can be traced back to Fred Silverman in 1969 who was the head of Daytime Programming for
CBS. Silverman was looking for a show that would lead the network away from the superhero cycle and take them into an area
of comedy and adventure.
The combination of Carleton E. Morse's 1940's popular radio program I Love a Mystery, in which three detectives roamed the world solving crimes and mysteries, and the 1959-1963 television sitcom The Many Loves of Dobie Gillis, about a scatterbrained teenager and his friends, was the look Silverman was after. Silverman's quest was brought before Hanna-Barbera who assigned writers Ken Spears and Joe Ruby to create the characters, plots, and many of the story lines. The show actually started out revolving around four teenage detectives who traveled the country in a van, called the Mystery Machine, solving mysteries in dangerous situations. A Great Dane accompanied the foursome but was not a promient character. The show was first known as Mysteries Five and later changed to Who's Scared? The show was then presented to the top CBS management and president Frank Stanton as a new Saturday morning cartoon for the fall of 1969.
There was one problem: the artwork was very frightening which led Stanton to reject the show. Silverman immediately flew
back to Los Angeles that night. While listening on the earphones on the flight back, Silverman was relaxing to Frank
Sinatra singing Strangers in the Night. The phrase 'Scooby-Dooby-Doo' struck Silverman so much that he went back and said
'We'll call the show Scooby-Doo, Where Are You? and we'll make the dog the star of the show.' And with those words Scooby-
Doo was created with the other characters supporting him.

The new show was now more comical then mysterious. Don Messick became Scooby with his trademark laugh and scratchy voice. This role would remain Messick’s biggest and best-known. He voiced the Great Dane through all of the various versions of Scooby-Doo: on TV in numerous formats from 1969 to 1985, four telefilms, and a number of commercials as well. Messick was still voicing the role when A Pup Named Scooby-Doo came along from 1988 to 1990.
Top-Forty DJ Casey Kasem became Shaggy who was always in a constant state of panic and hunger which also served as Scooby's partner. He also walked out on his role as Shaggy in 1995, when he was asked to voice Shaggy in a Burger King commercial. Kasem – a vegetarian – felt that that was inappropriate for the character, whom he wished also to be a vegetarian. He returned to the character in 2002, after Hanna-Barbera agreed to portray Shaggy as a strict vegetarian, notwithstanding the fact the Shaggy has been seen by countless viewers gorging himself on any food in sight, including plenty of meat, since 1969.
Frank Welker became blond Freddy, the level-headed leader of the mystery-solving team. As of 2002, Welker is the voice of both Fred Jones and Scooby-Doo in What's New Scooby-Doo?
Nicole Jaffe became brainy
and bespectacled Velma. Velma was Jaffe's only voice role. Like her character, Jaffe was myopic and needed glasses or
contacts to see. At the first voice recording rehearsal for Scooby-Doo, Where are You!, Jaffe accidentally dropped her
glasses and cried out something to the effect of "my glasses! I can't see without them," which became a trademark gag
and catch phrase for Velma.
The trouble-prone, sexy Daphne was the voice of Heather North. North was the second actress to voice Daphne, Stefanianna Christopherson voiced the character during the first season of Scooby-Doo, Where are You! in 1969.