They can arise from legal agreements between the relevant copyright holders (known as intercompany crossovers), common corporate ownership or unofficial efforts by fans.
Unofficial crossovers often take the form of fan-written fiction[1] and fan art, but the trope is increasingly prevalent in amateur films and audio.
Roger, Rallo Tubbs, and Klaus Heissler were seen in the final Family Guy Star Wars spoof, "It's A Trap!
In comic book terminology, these "guest star" roles are common enough that they are generally not considered crossovers; rather, this short-term collaboration to fight crime is called a team-up.
This story dealt with Zatanna attempting to reconnect with her father, Zatara, and seeking the aid of Hawkman, Batman, Robin, the Atom, Green Lantern, and the Elongated Man along the way.
As a way to further toy sales he devised the Secret Wars crossover which brought all the major Marvel heroes into a 12-issue miniseries to battle a common threat.
Secret Wars was hailed as both a critical and commercial success, largely because the events of the crossover had lasting effects on the characters (such as the introduction of Spider-Man's black suit which would later become the villain Venom).
Cartoon crossovers are not uncommon, and most of them – like comics or live-action TV shows – will often feature characters owned by the same company or network.
It features five crossovers – Ed, Edd n Eddy, Codename: Kids Next Door, The Grim Adventures of Billy & Mandy, a reference to The Powerpuff Girls, and a quote from Scooby-Doo, which are all licensed Cartoon Network series.
Some of the earliest examples happened on The New Scooby-Doo Movies which featured appearances by characters from Harlem Globetrotters, Josie and the Pussycats, Jeannie, Speed Buggy, Batman and Robin, and The Addams Family.
Later, the Hanna-Barbera Superstars 10 set of movies involved several crossovers, including such combinations as The Jetsons Meet the Flintstones.
In addition to this a couple of characters from Eddsworld make appearances in some Crash Zoom episodes such as "Orcs and Dorks".
One of the biggest projects down would be Dream 9 Toriko x One Piece x Dragon Ball Z Super Special Collaboration as it includes three Shonen Jump franchises, being Dragon Ball Z, One Piece, and Toriko, crossed over into an hour long special-like most crossovers, this special is filler, a fan-service episode that follows the common plot line in most crossovers.
Inspired by Marvel's success, Warner Bros., who hold movie rights for DC Comics' heroes, announced the production of Batman v Superman: Dawn of Justice (2016) and further plans to develop the cinematic DC Extended Universe, while Paramount Pictures and Entertainment One announced plans to create a cinematic universe on the Transformers film series.
Godzilla, Mothra and Rodan (Radon) each first appeared in standalone films before being set against each other or even teaming up against stronger enemies.
The first popular crossover in literature was the 1885 Mark Twain novel, The Adventures of Huckleberry Finn, which had an important guest appearance by Tom Sawyer.
Salinger, William Faulkner, Margaret Laurence, Thomas Pynchon, Kurt Vonnegut, Mordecai Richler, Sir H. Rider Haggard, Edgar Rice Burroughs, Robert Heinlein, and Isaac Asimov also cross over with each other, linking different characters and settings together over a number of different works.
In it, a nameless narrator is transported to "Twilight Land" and meets famous fairy tale characters for a soirée in an inn: Mother Goose, Cinderella, Fortunatus, Sinbad the Sailor, Aladdin, Boots, the Valiant Little Tailor, and others gather in the framing device and tell each other adventurous tales featuring other literary personages.
[5][6] It is also common for authors to 'crossover' characters who have passed into the public domain, and thus do not require copyright or royalty payments for their use in other works.
Crossovers involving principals can also occur when the characters have no prior relationship, but are related by time period, locale or profession.
The Law and Order series, for example, afford a commonality of setting and profession which lends itself to crossovers, both within the franchise and in a wider universe.
Crossovers can take the form of a promotional cameo appearance, used to draw attention to another work of fiction, with little rational explanation in the context of the hosting show's narrative.
A notable example of this is The Simpsons episode "A Star Is Burns", in which the character of Jay Sherman (from The Critic) appeared.
This episode was largely condemned by fans of The Simpsons as existing to promote The Critic, an animated series considered inferior by comparison.
Even Simpsons creator Matt Groening objected, preferring to remove his name from the credits of that particular episode in protest.
An obvious example of this type of crossover occurred when Cliff Huxtable of The Cosby Show visited his daughter, Denise, on A Different World.
More complex multi-production franchises can utilize crossovers of characters to serve as a device in establishing continuity in a shared fictional universe.
However, on rare occasion, the humor of such crossovers can be used by one show make a narrative point by capitalizing on the audience's experience of the other program.
It has more recently been used to demonstrate that cast members of The Young and the Restless appeared in a dream of a character on The King of Queens.
Their respective popular heroes Horst Schimanski and Peter Fuchs join forces to solve a case in the turmoil of the time after the fall of the Berlin Wall.