Mrs. Chaka and I started talking tonight about science-fiction/fantasy franchise crossovers. You know, like how since Star Wars took place a long time ago in a galaxy far away, and time travel happens in every third Star Trek movie, you could have a movie where the Enterprise joins in the attack on the Death Star. (This crossover is Mrs. Chaka's idea. I had not fathomed that such a thing was possible.)
That reminded me that I had heard of a Star Trek/X-Men crossover (apparently what I was thinking of was this comic book). If they did a movie crossover, Patrick Stewart would get to negotiate between the Federation and the X-Men as both Captain Picard and Professor Xavier. That scene makes the whole project worth doing.
And from that point, we tried to connect the cardinal science-fiction and fantasy franchises to each other. Jim Broadbent connects Harry Potter and Narnia; Christopher Lee connects Star Wars to Lord of the Rings . . .
It took some brain-racking (and eventually some help from IMDb), but this is what we came up with:There are other, more marginal franchises we could tack on: Batman, X-Men, Terminator, Pirates of the Caribbean. But they would destroy the symmetry of the above.
Incidentally, several of these franchises to Kingdom of Heaven. I'll let you flesh out the connections in the comments.