A couple of characters that I headcanon as autistic:
1) Groot: A nonverbal autistic, Groot can struggle with self-care and appropriate social behaviour. Groot is very empathetic and loves to spend time with his friends, but can get distracted by his need for oral sensory stimulation.
2) Drax: A very literal autistic who struggles with interpersonal relations and figurative speech, Drax’s bluntness often comes off as abrasive. Considered neurotypical for his people, Drax never had functional issues within his own society, a fact which causes him much frustration.
3) Superman/Clark Kent: A hypersensitive, hyperlexic autistic, Superman experiences regular sensory-overload and navigates interpersonal interactions with the aid of complex scripts. He has trouble with eye-contact unless in his Superman persona and often comes off as shy and/or overly formal. He needs a lot of time alone, and regularly zips off to remote places to get some peace. Luckily, flying is the best stim in the world.
4) Superboy/Conner Kent (Young Justice): A hypersensitive autistic like his dad, Superboy is much more likely to experience meltdowns/shutdowns. He is often literal and needs help navigating confusing social experiences and emotions. His tendency to info-dump was magnified by the way in which he was taught, but luckily his friends don’t mind. He prefers hiding in small places, since he can’t fly (gddamnit), and watching the “snow” on the TV.
5) Hulk: An abused, hypersensitive, mostly nonverbal autistic, Hulk experiences almost constant meltdowns where he becomes physically violent in an attempt to control the chaos he experiences. With a poorly developed theory of mind, Hulk usually has trouble thinking about things from other people’s perspectives and has a lot of trouble interacting with people. A fan of destructive stims, Hulk is regularly assaulted with ableist prejudices, and is often thought of as being less-than-human. Fortunately, the Avengers are good friends and always have something for Hulk to Smash.