I'm going to be speaking at Can-Con (The Canadian Conference for Speculative Fiction) on portrayals of autism in fiction over the Halloween weekend. (Well, not the whole weekend, I presume they'll only let me natter for an hour ... or less since other people will be talking about it, too.)
It's gotten me thinking about the common portrayals of people with autism. They seem to fall into two categories: the savants and the punchlines.
Rainman would be an example of savantism. I've also seen it done in shows like Criminal Minds and Law and Order, where a child or adult with autism displays their ability to play a piece of music after hearing it once or can recite all the licence plates at a location from 3 days previous.
Sheldon on The Big Bang Theory would be a well-known example of autism as a punchline (although the writers have been very careful to avoid saying he has autism). In general, when it's being played for laughs, autism is used as an excuse for being a jerk. That one bothers me a great deal because while people with autism can be brusque or unaware, they are not deliberately mean or offensive.
After some careful thinking, I've come up with my three best examples of autism portrayals:
1) "Lines in the Sand" an episode of House, season 3, episode 4. A 10 year old boy with autism is brought to Dr. House's team, screaming in pain. Since he is non-verbal, he is unable to tell them what is wrong or respond to their questions. Braeden Lemasters does a fantastic job in portraying the little boy. He avoids looking at people, he doesn't react to what they're saying, he rocks and moves repetitively, he's obsessively focused on his visual stimuli, his parents have had to give up their careers to work with him (they still have a huge house and resources, but I'll let that slide), his day is scheduled in 5 minute intervals for predictability. They even use Picture Exchange Communication properly.
2) Elizabeth Moon's The Speed of Dark, a novel done in first person from the perspective of a man with severe autism. Lou's confusion over understanding what people mean (he can't understand that another character is being mean to him because they are "friends") and his fascination and ease with patterns are a great insight into how an autistic mind can work.
3) Benedict Cumberbatch in The Imitation Game, although I would only count the parts of the movie which take place during World War II. The job interview and the lunch/sandwich conversation are brilliant examples of misreading social cues and taking things obsessively literally.