When it comes to Hollywood, there are plenty of universes that fans want to see cross over: Star Wars and Star Trek, Marvel and DC, all of the Universal monsters...there's something special about watching characters from two different franchises interact. It's almost like forbidden fruit; these two things shouldn't be mixed together, but they are.
Of course, there are plenty of mash-ups that aren't so conventional - two franchises that seem to have very little to do with one another, but once they're mixed, it just feels right. Case in point: HBO's True Detective and cult classic The Big Lebowski:
For comparison's sake, here's the original True Detective opening:
It's amazingly spot on. Aside from a few edits that would have required an entire film crew and new footage, the mash-up is perfect. It's amazing how well Epidemic Productions was able to capture the feeling of True Detective without sacrificing any of what made The Big Lebowski great.
Maybe it's time to get on the horn with HBO and Mr. Goodman - there's some real potential here for the third season of True Detective.