Great question. I’m not OP. But a bunch come to mind.

Disclaimer: Even in recent classic eras of science fiction, it wouldn’t have been safe for authors (who need publisher trust to buy food) to get diagnosed as neurodivergent, so I feel like we’re left with wether neurodivergent individuals embrace their work, rather than if the author ever acknowledged any personal neurodivergence.

Disclaimer: I’m not neurodivergent. I don’t feel safe seeking a diagnosis. And things aren’t binary, so what the hell. I do acknowledge it’s interesting that I relate strongly with a bunch of these characters, and can bring them to memory quickly as some of my favorites…

With that disclaimed:

• “The November People” by Ray Bradbury comes to mind. It explores how classic Hollywood “monsters” would handle themselves as roommates, mostly through exploring their mental diversity rooted in their physical/cultural differences.
• Asimov’s robot detective stories (start with The Caves of Steel) have protagonists whose planets effectively make them neordivergent anytime they visit another planet than their birth world.
• “Stranger in a Strange Land”, by Heinlein, is about a neurodivergent (for Earth) young man who grew up as the sole human citizen of Mars.
• Philip K Dick’s detective protagonist from “Do Androids Dream of Electric Sheep” (aka Blade Runner) is clearly neurodivergent, as is his wife.

Edit: As others have mentioned, Mary Shelly’s Frankenstein, of course!