CROSSOVER WRITER STAMP

Another fan fiction subgenre is the crossover story, in which either characters from one story exist in (or are transported to) another pre-existing story's world, or more commonly, characters from two or more stories interact.

While the crossover genre is extremely popular amongst fan fiction writers, it does sometimes occur in canon works – examples of this include the video game series Kingdom Hearts which crosses numerous Disney works with those of SquareSoft, and an episode of The X-Files which featured Richard Belzer as his Homicide: Life on the Street character John Munch... who also later began to appear as a main character in Law and Order: SVU.