"Animation is simply a form of expression, and can be used to great effect for any genre or target audience," said Sam Matthews, the son of a children's film maker.
Matthews watched animated shows and movies growing up (as many of us did), but his tastes have changed with his age (as many of ours have.)
"Western culture has come to regard animated media as being strictly for children, but influences from other cultures are starting to shift this trend for westerners," said Sam. More and more animated shows and films are being created to be entertaining for adults watching it with their kids, and some are even being created for adults only. Adult Swim is an entire network created to showcase (mostly) animation targeted at adults. However, most of these shows seem to be targeted at inebriated 16-29 year olds, and it barely skims the breadth of the history of adult animation.
You've probably heard of South Park and The Simpsons, and the whole line up of Seth MacFarlane shows (Family Guy, American Dad, The Cleveland Show). There is also a huge amount of anime targeted towards adults. Here is a list of the top 6 western shows and films for grown-ups that you may not have heard of, but which are fairly great.
*Also, recognize that the clips are to various extents NSFW!*
6. Clone High (2002-2003)
Why it's for adults: It's about historical figures children wouldn't remember. Some references to beer and sex.
Why it's great: Clone High was a series that ran for one season about teenage clones of historical figures, like Abe Lincoln and Ghandi. The characters were well-developed, and the humor was at once understandable and smart (In shop class, Caesar warns a careless clone of Jesus Christ, "Be careful with that nail gun, Jesus!")
Why it's for adults: Animal abuse, some violence, sad ending.
Why it's great: The Plague Dogs was written by the same author of Watership Down, and it follows the escape of two dogs from a testing facility. The film features an attempt to escape human oppressors, a descent into insanity, and a terribly emotional ending.
Why it's for adults: Extreme violence, references to sex and alcohol.
Why it's great: Superjail! is a series on Adult Swim with incredible, psychadelic animation. Each episode starts with a somewhat benign plot in a super huge jail (in a volcano in another volcano), but things soon go awry. Colors swirl, insanity ensues, and the inmates are massacred in terrible, bloody numbers, but it's completely hilarious in the emphatic randomness.
Why it's for adults: References to violence, sex, and drugs, language
Why it's great: Spicy City was the first animated adults-only show, created by cartoon bad-boy Ralph Bakshi. What's noticeable here is not the animation or the adult themes but the intense philosophical issues related to the mind and body. In one episode, characters who are in love destroy their bodies to exist together in a virtual game, and in another a man searches for his daughter but accepts a clone as substitute. If any series will make you think, it's this one.
Why it's for adults: Gross humor, smoking, references to sex
Why it's great: Yes, it may be hard to believe that the beloved cartoon series of your youth was made into a short series for Spike TV, but the result was at times pretty great. While some of the episodes are reminiscent of the gross humor for which Ren and Stimpy are famous, (taken to an even higher degree,) the more adult humor was even funnier. The most amazing part of this series, though, was the incredible animation. The characters' actions are emphatic and humorous, and their elasticity and caricaturized faces demonstrate real mastery of animation.
Why it's for adults: Sex, drugs, violence
Why it's great: Fritz the Cat was well-known when it came out, as it was the first X-rated animated feature film. The story involves a college student, who is also a cat, who is caught in the 1960's intersection of sociopolitical activism and hedonism. While the adult elements are salient, the plot is very good as well, and it should make you think. It was directed by Ralph Bakshi, and it marks the historical moment when western animation extended its reach to adult humor and themes.
These pieces are alternatively humorous, beautiful, insane, shocking and emotional. Hopefully these examples exemplify the reasons that adults can enjoy cartoons just as much as our younger selves.