The Flintstones was originally intended for adults. Itwas The Simpsons of its day, appearing during prime time. Sponsored by cigarette companies, and I think you can find some of the old ads of Fred and Barney pushing smokes on YouTube.
Another vote for The Venture Bros., which is a brilliant parody of all sorts of Saturday Morning Cartoon and Superhero/Supervillain stuff, Space Age Retro-Futurism, and Science!, and also has a decent and coherent plot with a lot of complexity and layers to it.
Otherwise, you’ve got Futurama, which (despite being a comedy) also deals with some Big Issues (I dare you to watch the Jurassic Bark episode and not “have something in your eye” at the end!), and I think King Of The Hill deserves an Honourable Mention for being pretty close to an animated drama (albeit one with strong comedic elements) too.
Tripping the Rift is indeed available on DVD. I have the first 2 seasons as well as the movie. IMO, only the first season is worth watching. Gina Gershon voiced Six for those episodes. She was replaced by Carmen Electra in season 2, much to the detriment of the show. Jenny McCarthy was brought on board for season 3, but by then I had lost interest in the series as the writers seemed to have lost any sense of what the show was about and were just rehashing old plots.
Stripperella by Stan Lee and voiced by Pam Anderson was certainly aimed at an adult audience.
Do they have to be series? There are a few animated dramas in movie form, like ‘When the Wind Blows’ (an ordinary elderly couple try to cope with a nuclear disaster; might make you cry) or Persepolis (rebellious girl grows up in a changing Iran).
Disney’s ‘Gargoyles’ bordered, especially the deeper they got into their original run, on being a very grown up oriented series. Not too many series meant strictly for kids manage complex story arcs, or deal deeply in Shakespeare, history and world mythology, the way ‘Gargoyles’ did.
Still a kid’s series? To a point. For Disney at the time, though, this was something rather groundbreaking. It was pretty serious stuff.
Another vote for Venture Bros. It is most decidedly not for kids; it’s for people who used to be kids. You can’t get the jokes otherwise.
Another vote for Gargoyles, while I didn’t catch the entire run, it had very sophisticated themes and story arcs.
I’m surprised that there can be so many votes for *Metalocalypse *without any mention of the far superior Home Movies. While *Metalocalypse *has fantastic metal and ridiculous gore, Home Movies has a lot more range, thematically and musically. It’s honestly funnier and more mature, which is odd to say about a show with an eight year old lead character.
Like Venture Brothers, it’s a show for people who used to be kids.
So was Wait 'til Your Father Gets Home over a decade later. It didn’t have prehistoric gags, and tried to be “relevant”, and folded and disappeared completely from view. I’ve never seen a home video release, although Wikpedia claims the first season came out on DVD.
There are some excerpts on YouTube: