The Flintstones, a cartoon classic, you might not know that this show originally aired on primetime television and was once the longest syndicated cartoon until The Simpsons came around. While its content is a tad archaic for today’s sensibilities, it’s still one of the most popular and beloved cartoons of all time. It single-handedly built Hanna-Barbera’s company. Plus, you probably have the theme song running in your head right now, don’t you?