Answer
More than 300 million people enjoyed Hanna-Barbera's shows in their 1960s heyday. This makes Hanna-Barbera one of the most successful animation studios in history. Some of Hanna-Barbera's most popular shows from this era include The Flintstones, The Jetsons, and Scooby-Doo. These shows were not only popular in the United States, but also around the world. Hanna-Barbera's success in the 1960s helped to establish animation as a major form of entertainment.