There’s no mystery when it comes to the enduring popularity of the Scooby-Doo characters. The children’s mystery franchise, which turns 55 on Sept. 13, 2024, introduced the world to the Scooby Gang — comprised of the charming Fred Jones, fashionable Daphne Blake, studious Velma Dinkley, quirky Shaggy Rogers and the eponymous mascot, Scooby-Doo. Also known as Mystery Inc. and the Mystery Gang, the five characters have stood the test of time across dozens of TV films, series and video games. Fred, Daphne, Velma and Shaggy have been played by several actors each as the franchise has launched animated series and...