When most people are asked what the first animated series on American network prime time television was, they will most likely say The Flintstones. As it turns out, they would be wrong. The Flintstones was not the first animated series to air in American prime time. In fact, it wasn't even the first animated series on American television aimed at adults. That honour would go to another series.
That series was CBS Cartoon Theatre. In 1955 Paul Terry, founder and owner of the animation studio Terrytoons, retired. He sold the studio (home to such characters as Mighty Mouse and the team of Heckle and Jeckle) lock, stock, and barrel to the Columbia Broadcasting System, even though 20th Century Fox would continue to distribute Terrytoon's theatrical shorts. CBS put Gene Deitch, late of UPA, in charge of the newly acquired studio. Deitch would not last long at Terrytoons, as he clashed with many of the studio's old timers, but he would breath new life into the studio. Namely, it was on his watch that a new animated series, "Tom Terrific," was created for the then young series Captain Kangaroo, as well as such characters as Gaston Le Crayon and Sidney the Elephant were created. Among the young talents he brought to the studio was Jules Feiffer.
CBS itself would put the old Terrytoon theatrical shorts to good use. The first thing they did was to make history with the first Saturday morning animated series, Mighty Mouse Playhouse. Mighty Mouse Playhouse was essentially an anthology series consisting of Terrytoons' old theatrical shorts. It proved to be a roaring success. Not only did it pave the way for all Saturday morning cartoons to come, but it would last eleven seasons itself. It debuted on December 10, 1955.
Like Mighty Mouse Playhouse, CBS Cartoon Theatre was a collection of old Terrytoons shorts. Unlike Mighty Mouse Playhouse, it would not be successful. CBS was eager to capitalise on the success of ABC's Disneyland, so they created a somewhat similar show. CBS Cartoon Theatre was hosted by a young comedian named Dick Van Dyke, who hosted the show from an office setting not unlike Walt Disney on Disneyland. Van Dyke would interact with Terrytoons' various animated characters, such as Heckle and Jeckle and Gandy Goose, in the live action opening segments and bridge segments. The major difference in the formats of the two shows was that Disneyland primarily aired live action, while CBS Cartoon Theatre was purely an anthology of animated shorts. While CBS Cartoon Theatre marked the first time an animated series, albeit an animated anthology series made of previously released material, aired on network prime time television, it would not be a success. CBS Cartoon Theatre only lasted thirteen weeks and was not picked up for the fall. Apparently CBS Cartoon Theatre could not compete with Disneyland, not even in reruns. It debuted as a summer replacement on Wednesday, June 13, 1956 at 7:30 PM Eastern Time.
That would not be the end of Terrytoons on CBS's schedule by a long shot. They would follow up the success of Mighty Mouse Playhouse with The Heckle and Jeckle Cartoon Show, which debuted on Saturday morning on October 1956. The Mighty Heroes, created by Ralph Bakshi, would air for one season on the network in the 1966-1967 season.
Of course, here it must be pointed out that The Flintstones wasn't even the second animated series to air in prime time. In 1956 CBS debuted The Gerald McBoing-Boing Show, a collection of UPA theatrical shorts. It was narrated by radio announcer Bill Goodwin and aired on Sunday evenings at 5:30 Eastern Time. Ultimately the series proved too expensive to produce and was cancelled after three months. It would be rerun during the summer of 1957 in prime time on Friday nights, making it the second animated series to air in prime time.
Both the Terrytoon shorts and especially the UPA shorts (which could be fairly sophisticated) were made with adult audiences, rather than children, in mind. After all, these theatrical shorts were meant to be run before feature films which had been made for adults or, at least, audiences of all ages. The Flintstones was then not even the first animated series aimed at adults.
That having been said, The Flintstones does have a firm place in history as the first animated series composed of entirely new material to air in prime time. Both CBS Cartoon Theatre and The Gerald McBoing-Boing Show were anthology series consisting of previously released, theatrical shorts. The Flintstones was an entirely new series produced by Hanna-Barbera Productions. It would prove more successful than either CBS Cartoon Theatre or The Gerald McBoing-Boing Show, lasting a total of six seasons.
Of course, even the success of The Flintstones would not guarantee that animation would be regularly seen on network prime time television. After a very brief cycle towards prime time cartoons in the early Sixties which spawned both The Jetsons and Jonny Quest, it would not be until the Nineties that a significant number of animated series would debut on network prime time television. Even after the success of The Simpsons (set to become the longest running scripted primetime series with continuing characters after this season) and King of the Hill, animation in prime time is a rare thing. Regardless, it all started with a collection of Terrytoon shorts hosted by Dick Van Dyke.