Scooby-Doo is the longest-running United States animated franchise produced for Saturday morning television in several different versions from 1969 to the present. Though the format of the show and the cast (and ages) of characters have varied significantly over the years, the most familiar versions of the show feature a talking Great Dane named Scooby-Doo and four teenagers: Fred Jones, Daphne Blake, Velma Dinkley, and Shaggy Rogers.
These characters drive around the world in a van called the "Mystery Machine", and solve mysteries typically involving tales of ghosts and other supernatural forces. At the end of each episode, the supernatural forces turn out to have a rational explanation (usually a criminal of some sort trying to scare people away so that they can commit crimes).
Below are the characters found available on the site that cosplayers have depicted.