{{Crossover}}s occur any time characters from one work "cross over" into another. Any time characters from one work interact with another work, you have a crossover.

This is extremely common in FanFic, where the authors take someone else's characters and play with them, often introducing a new setting or new characters in order to better facilitate the story they want to write.

This is an index of the varying types of crossovers; RuleFifty may apply to some of these.

[[index]]
* BatFamilyCrossover
* CanonWelding
* CharacterOverlap
* CommonCrossover
* CrisisCrossover
* {{Crossover}}
* CrossThrough
* CrossoverPunchline
* CrossoverShip
* DeconstructionCrossover
* DoppelgangerCrossover
* FakeCrossover
* FullyAbsorbedFinale
* FusionFic
* GuestFighter
* HypotheticalFightDebate
* IntercontinuityCrossover
* LawyerFriendlyCameo
* MassiveMultiplayerCrossover
* ModularFranchise
* OfficialParody
* OriginalGeneration
* PoorlyDisguisedPilot
* PowerCreepPowerSeep
* RedSkiesCrossover
* RequiredSpinoffCrossover
* StoryBreakerTeamUp
* SpotlightStealingCrossover
* TeamUpSeries
* {{Transplant}}
** RoguesGalleryTransplant
* UltimateShowdownOfUltimateDestiny
* TheWorldAsMyth
[[/index]]
----