Those Beatles cartoons are the reason the Beatles did not provide their own voices for the animated portions of “Yellow Submarine”. Fearing another crappy product, they said ‘no thanks’. But after seeing that the production quality was so much better than they expected, they expressed interest in voicing their own animated characters. But it was too late for that. So they agreed to the live-action sequence at the end of the film.
There was one for the Dukes of Hazzard, where the Duke boys were in a race around the world with Boss Hogg and Sheriff Roscoe. The worst part was that it was made during that short period where Tom Wopat and John Schneider were off the show. The Duke boys were Coy and Vance. They did replace them with Bo and Luke in the second season, but Saturday cartoons always shorted the second season. First season was usually 12-13 episodes and the second season was 6-7 episodes. That’s why it always seemed like those cartoons were always in reruns.
The voices they did choose are kind of interesting. The George Harrison voice actor was a British army deserter and was arrested before they completed his part. And the voice of Paul was Geoffrey Hughes of Coronation Street and (probably best known to Americans as) Onslow from Keeping Up Appearances.
Actually there were two animated spinoffs, The New Adventures of Gilligan and Gilligan’s Planet, both from Filmation and both featuring almost the entire original cast. The first ran for 24 episodes in the mid-1970s and was set on the island. The second had the characters traveling into space and getting marooned on another planet. It ran for 12 episodes in the early 1980s.
Of which, *Q-bert *was by far the worst!
Filmation’s Hardy Boys (1969-1971) …absolutely terrible.
Don’t forget… Ghostbusters (1986) which was a remake of the live-action sit-com The Ghost Busters (1975)
“The New Scooby-Doo Movies” had “celebrity guests” in every episode, from Sonny and Cher to Laurel and Hardy to the Addams Family.
There was also the ProStars in 1991 starring Michael Jordan, Wayne Gretzky, and Bo Jackson. Despite being a fan of Saturday cartoons, somehow I never had the opportunity to watch this…
I thought I was the only one who remembered that cartoon. And it wasn’t a parody. It was a real Saturday morning kid’s show.
The Harlem Globetrotters (twice!) from the aforementioned animated series, The Three Stooges (based on their 1965 animated series), Batman & Robin…
The Napoleon Dynamite cartoon TV series.
As a fan of the movie the cartoon was just… horrible.
They made 6 episodes and Fox never asked for more.
That was much too good to be a candidate for this thread, varying from “impressively good” (“Yesteryear” in particular) to “eh, not as bad as some of the drek Trek from the third live-action season”.
Now, for bad animated adaptations, I give you The Brady Kids.
And while “the Brady Bunch” was never a great show, it is a stunning work of greatness compared to the Brady Kids from the early 1970s.
As a bonus, the linked YouTube clip also shows the first, and arguably worst, animated adaptation of the character Wonder Woman. (Fun fact: the character “Wonder Girl” - a spinoff character - actually beat Wonder Woman into animation. She appeared in the late 60s “Teen Titan” cartoons.)
I’ve only recently discovered that there was an animated series of Supernatural. I haven’t seen it, but I want to.
There was an animated version of Kevin Smith’s Clerks. Only six episodes were produced, and only two ran on ABC before it was quickly canceled. All of the episodes eventually aired on Comedy Central. It was quite tame compared to the movie. For example, instead of Jay and Silent Bob peddling drugs in front of the Quick Stop, they sold illegal fireworks.
While it was toned down for network standards, it was actually a fairly good adaptation. It had decent animation and some clever ideas. The second episode of the series was a clips episode featuring the main characters getting locked in a store room and reminiscing about scenes from the first episode. (Unfortunately, this gag was lost on most viewers since the network showed the episodes out of order, so anyone who’d tuned in the previous week still wouldn’t get the joke.)
I remember suffering through each episode because I liked “Space Ace”. 1 in 6 is bad odds.
This was going to be my nomination, as well. 
I remember the partridge family cartoon being shown in a block with other weird cartoons like the I dream of Jeanie ripoff ect in between flinstone comedy skits and they cut them up so they could 4 or 5 series at the same time
took a week for 1 complete story
fun fact :they recycled the the cartoon plot for the dukes of hazard playstation one game although I never played it
and we could start another thread for horrible video game cartoons