Batman Vs. Aliens (The Movie!)

 I remember a pretty well done Batman Vs. Aliens mini-series in comic book form back in the day, but how cool would a live action version of that match up been?  Get Ridley Scott or James Cameron back to direct and that would have been quite the blockbuster!

Superman is an Alien

 

It's good to see both of these movie franchises back on more solid footing.  James Gunn's Superman looks promising and Alien: Romulus is my favorite entry in that series since the first two movies.  It might have been cool to see a crossover back in the 80's.