The 13 Ghosts of Scooby-Doo brought about several significant changes to the long-running Scooby-Doo franchise, which began in 1969 with Scooby-Doo, Where Are You! No longer pitted against criminals in rubber masks posing as ghosts, the gang now had to defeat real ghosts in order to save the world. It was their own fault, really. Scooby and his friends were duped by the ghosts Weerd and Bogel into opening the "Chest of Demons," which imprisoned thirteen of the most terrifying ghosts ever to have roamed the Earth. Since they were the ones who released the ghosts, only they could return the demons to the chest. Thirteen ghosts... thirteen episodes in the series; in the end the gang turned out to be just as good at catching real ghosts as they were at exposing the fake ones.
The cast from The New Scooby-Doo Mysteries, which aired the previous season, returned for this series. In addition to Shaggy, Scooby, Scrappy and Daphne, two new regulars were added to the lineup. Accompanying the gang was a young boy named Flim Flam. A pint-sized con artist, Flim Flam used his skills to good effect when his friends were in a jam. The gang also received the help of the powerful warlock Vincent Van Ghoul — a cartoon caricature of Vincent Price, who also provided the character's voice. Van Ghoul remained in his castle sanctuary, but he provided information and guidance for the group by contacting them through a crystal ball that the gang carried with them when they were on the road.
The two bungling ghosts who started all the trouble, Weerd and Bogel, did their best to hinder the gang from catching any of the escaped ghosts. More nuisance than menace, however, their interference rarely caused much concern.
Of interest to longtime fans of the franchise, after sixteen years Shaggy and Daphne were finally given a new look. Shaggy was outfitted with a red shirt and blue pants in place of his usual green shirt and red pants. Daphne's makeover was more drastic, providing her with a new hairdo and attire befitting 1980's fashion. Her wardrobe was uncommon for a cartoon series in that it changed from one episode to the next.
In 1988 the original Mystery, Inc. gang (which included members Fred and Velma) were finally reunited as younger versions of themselves in A Pup Named Scooby Doo, but the kids wouldn't resurface again as teenagers until 2002, in What's New Scooby-Doo?