I had a classmate in second grade who was diagnosed with autism. Had the most violent of meltdowns and did not speak most of the time. When he was heard, he was singing out his sentences, if that makes sense.
In seventh grade, I had another classmate with ASD. She was very nice and had a best friend who she was always seen with. He bought her chocolates and flowers on Valentine's day and it was quite a sweet sight.
In high school, I encountered someone I thought who may have ASD. I was told by a friend that this person had a diagnosis, but I'm not certain. He would come to school early to finish homework he didn't do the night before. I would come to school early to do the same thing. He noticed this was part of my routine, and then made it part of his routine to buy me breakfast the school offered. Every morning. He seemed hurt when I declined, so I just took him up on the offer.
In college, I thought another classmate may have ASD, although he had some bewildering characteristics. He was extremely good looking but girls would recoil when we had class conversations on politics. He was very blunt and in all seriousness believed that women should be held to a higher standard when testing for their driver's license. He seemed to be in a lot of monogamous relationships, and broadly advertised details of his sex life on Facebook. Some professors thought he was a bit off. I'm unsure as to what he had, really.
A girl who lives very near me claims she has it, but we're all doubtful, as she claims to have a bit too many things, often as an excuse for bad behavior. She doesn't seem to want feedback on why certain things she does are rude.
A guy I used to work with when cashiering very briefly told me upfront he had Asperger's. He was nice and very fastidious. Used to be a cameraperson for television news, but told me it was too overwhelming.