Wow nobody's mentioned "Revenge of the Nerds" yet?! C'mon. They're NERDS! Alright not all of the "nerds" in the movie had Asperger's 'cuz some (like Lamar) were outcasts for a different reason than their social behavior, but I'd say a lot of 'em had it.
Lewis had that goofy laugh and was also a bit naive in some parts of the movie.
Gilbert was an innocent but smart character (and his girlfriend Judy, even more so)
Wormser was a 12-year-old aerodynamics whiz kid who was already in college. How does that NOT scream "Aspie" to you?!
Poindexter was the stereotypical smart guy who was always afraid of everything and hardly spoke.
The other three "nerds" probably didn't have it. Lamar I already mentioned, "Booger" seemed like more of a disgusting comic relief than a "nerd", and Takashi was a nerd by default simply because he was a foreign exchange student.
Other AS characters in movies and TV...Hmmm....
In "The Simpsons":
Lisa, of course, like a lot of people on the board have already said.
Ralph Wiggum is probably somewhere on the autistic spectrum, but not Aspie.
Milhouse seems like an Aspie, although mainly 'cuz he's a nerd
Comic Book Guy as well since he relates better to fictional characters than real ones
Professor Frink, for similar reasons to Milhouse
In "Spongebob Squarepants":
Spongebob, since he's emotionally immature and oblivious to how others think of him.
Squidward, since he's antisocial and has specific special interests
In "The Big Bang Theory":
I'm tempted to say "every character except Penny" here - Sheldon...umm...well anyone who's seen the show would know why
Leonard, although more social than his peers, doesn't seem to get quite the hang of how to socialize properly.
Howard 'cuz he doesn't seem to notice his various rejections by women, he just keeps on doing what he's doing.
Raj is probably less Aspie than the other three though he does exhibit some traits of it when he tries to socialize with women.
Oh yeah, and Leslie Winkle as well though that's probably just 'cuz she's...well...a nerd
In "Sesame Street":
I think pretty much every Muppet character on the show had some kind of diagnostic behavior, esp. the '70s and early '80s characters:
Big Bird (at least the original Big Bird before they decided his age was 6) had arrested development, and even after that he was thought of as being delusional 'cuz he was the only one who could see Snuffleupagus
Ernie was oblivious to how Bert usually felt and had an obsession with his rubber duckie, so I think he's Aspie
Bert, of course, was WAY more Aspie since he was somewhat antisocial and had a love for odd things like paper clips, oatmeal, pigeons, and bottlecaps.
Grover seemed especially Aspie in those clips where he was taking orders from that Blue guy who kept shouting "Waiter!"
Cookie Monster and The Count both had OCD. One couldn't live without cookies and the other couldn't live without counting.
Kermit the Frog (yes, he was on Sesame Street AND the Muppet Show) seemed Aspie in those clips where he just couldn't control his temper when people would do things like continually goof up his name or sell him things he didn't want or goof up on one of their lines.
Oscar the Grouch is as antisocial as you can get. Might not have been Aspie, but he'd probably be diagnosed with something
Telly was totally OCD. He was a total worry-wart...and he also had that weird obsession with triangles. Also he tried to be friends with Oscar a lot of times, despite the fact that Oscar was...well...a grouch.
Prairie Dawn was normally calm, but she had her Aspie moments too being the control freak she was sometimes.
More modern characters like Elmo and Baby Bear didn't have anything. They were just little kids who acted like little kids to me.
In "The Breakfast Club":
Allison Reynolds 'cuz she had very eccentric behavior and was also very shy.
In "Rocko's Modern Life":
Filbert is totally hypochondriac/OCD so he might be Aspie.
Rocko probably is Aspie too since he gets easily annoyed by people (though I can't think of any other reason)
In "Napoleon Dynamite":
The title character and his two closest friends 'cuz they all seem to be naive and socially awkward.
In "Rugrats":
Chuckie 'cuz he always gets really scared of things really easily and also seems somewhat smart for his age.