Only Fools & Horses and Jack Ryan.

The Matrix and The Terminator. Skynet is the start of what eventually becomes the machines winning, and enslaving humanity! It's sort of a sequel storyline to Skynet and prequel to how the Matrix got started early on.

I know in Reloaded, Neo talks to the architect and he explains how early versions are rejected for being too perfect, so the machines had some trial and error. The T800s and other cybernetic organisms evolved into what are now the agents where physical terminators were too resource costly and needed to be virtualized for this new dream world.

The undertaker from wrestling goes into fast and furious and keeps bodyslamming dudes onto their cars

Dora the Explorer + Law and Order SVU

Doctor who and doctor strange

There should be a Muppets version of everything. It improves all source material.

The Power Rangers x The Great Gatsby

I must admit, personally I have no ideas for a crossover. But I wanted to reply so badly, I went to TV tropes and picked the first two IPs I recognized from clicking random media. Sorry

ThunderCats and Masters of the Universe (aka He-Man). I think there was a comic book once that did it, but I mean, like a movie. They've done a bunch of Transformers and they did Barbie, as far as modern 80s cartoon/toy adaptations. I think they've tried to do ThunderCats but the rights have been tied up or something. I feel like Masters of the Universe was objectively cooler, but ThunderCats was the one I watched. Looking forward to seeing the new MOTU in theaters this summer.

I think something like My Hero Academia and The Office would be pretty funny.

Show me the really mundane side of superheroes. The "Jenna, please file these by tomorrow" but Jenna is 12' tall. I think Dispatch comes close, but I want a whole ridiculous show. No heroics. Or even an isekai but in an office or normal job. Some mega powerful reincarnated whoever just needs to make some money.

Feels like that'd be funny.

Doctor Who and Star Trek would be fun.

I've said for years that we need one more episode of Celebrity Deathmatch between Delores Umbridge and Kai Winn

Avatar: The Last Airbender and His Dark Materials... What would the Gaang's daemons be? 👀

The Accountant and Jack Ryan. Ben Affleck and John Krascinski as their respective characters operating in the same universe would be cool. I think they would be an awesome pairing.

The Expanse and For All Mankind. It already feels a bit like FAM is a prequel anyway.

I used to have an awesome crossover idea but i can't remember it now! Damn it.

The owl house x game of thrones

Whatever gets us all in that autistic kid's snowglobes.