Literally anything can be crossed over into another universe. Take this interesting X-Men crossover with FX's Archer. It's weird, but the author makes it work (kinda).
Of Mutants and Marxists - Captain Lycan
WTF Did I Just Read? is a collection of fan-fiction read by us and in no means is meant to make fun of the authors or the themes discussed in them. You wrote it. We just read it.