Crossovers

A Crossover is a story which combines characters and settings from two or more separate fictional properties to create a single narrative.

Characters from various Disney-related universes have interacted multiple times throughout the companies history.

In some cases, it can occur in a self-contained scenario that has no relation to anything within a certain canon (various Disney movie characters appear on the show House of Mouse, with their appearances baring no relation to the established canon of their respective films). In other cases, properties that have their own established narratives and canon can interract, thus unifying said narratives as taking place in the same universe (various live-action Disney Channel sitcoms are strongly hinted to all occur in a single universe). Sometimes, different versions of characters from various properties coexist in a singlur universe (the Kingdom Hearts series is a prominant example of this). Crossovers have even occurred between Disney properties and characters and concepts from entirely different companies (Kingdom Hearts once again serving as an example).

Animated Canon

 * Wreck-It Ralph (film): the movie features cameos by characters from various video game properties, such as Pac Man and Sonic the Hedgehog. These cameos are all considered as separate from the characters respective canons.

Television

 * Hercules (TV series): the episode "Hercules and the Arabian Night" sees Hercules encountering the characters of Aladdin.
 * House of Mouse: the entire show revolves around Mickey Mouse and his friends operating the titular nightclub, of which various different Disney characters attend. Most of these attendees hail from movies in animated canon, though characters from old shorts, co-produced movies, and even animated TV shows have also appeared.
 * Lilo & Stitch: The Series: the show has crossed over with four of Disney Channels animated TV shows, implying the Lilo & Stitch canon and these four shows all exist in the same universe.
 * "Spats": a crossover with The Proud Family.
 * "Lax": a crossover with Recess.
 * "Morpholomew": a crossover with American Dragon: Jake Long.
 * "Rufus": a crossover with Kim Possible.

Disney Channel sitcoms
The the vast majority of live-action sitcoms that have aired on Disney Channel have been strongly implied to share a singular universe, due to various crossovers occuring between them. The shows that allegedly exist in this universe include That's So Raven (and its spin-off, Cory in the House), The Suite Life of Zack & Cody (and its sequel series, The Suite Life on Deck), Hannah Montana, Wizards of Waverly Place, Good Luck Charlie, Liv & Maddie, Austin & Ally and Jessie, as well the Disney XD show I'm in the Band.
 * That's So Suite Life of Hannah Montana is a three-episode crossover special between That's So Raven, The Suite Life of Zack and Cody, and Hannah Montana.
 * Wizards on Deck with Hannah Montana is a follow up special to the above, between Wizards of Waverly Place, The Suite Life on Deck, and Hannah Montana.
 * The Hannah Montana episodes "Take This Job and Love It" and "Don't Stop 'Til You Get the Phone" feature appearances by Cory in the House character Sophie Martinez.
 * The Suite Life's Marion Moseby appears in the Jessie episode "Karate Kid-tastrophe" where he's revealed to now be employed at the New York Tipton Hotel after the conclusion of Suite Life on Deck. In one scene, Moseby remarks on the phone to Cody Martin how much Jessie Prescott resembles Bailey Pickett (a joke referring to how Debby Ryan portrayed both characters).

Video Games

 * Kingdom Hearts (series): a collaboration between Disney Interactive Studios and Square Enix, surrounding an original overarching universe where the worlds of various Disney movies and properties coexist alongside characters from Square's Final Fantasy and The World Ends with you games.