In comic books, an intercompany crossover (also called cross-company or company crossover) is a comic or series of comics where characters published by one company meet those published by another (for example, DC Comics' Superman meeting Marvel's Spider-Man, or DC's Batman meeting Marvel's Wolverine). These usually occur in special "one-shot" issues or a miniseries.
Some crossovers are part of canon—for example, JLA/Avengers, which has been made canon in the DC Universe—but most are outside of the continuity of a character's regular title or series of stories. They can be a joke or gag, a dream sequence, or even a "what if" scenario (such as DC's Elseworlds).
Marvel/DC crossovers (which are mostly non-canon) include those where the characters live in alternate universes, as well as those where they share the "same" version of Earth. (Indeed, some fans have posited a separate "Crossover Earth" for these adventures.) In the earliest licensed crossovers, the companies seemed to prefer shared world adventures. They took this approach to the first intercompany superhero crossover, 1976's Superman vs. the Amazing Spider-Man, and followed the same format in 1981 with Superman and Spider-Man.
Besides the two Superman/Spider-Man crossovers, a number of other DC/Marvel adventures took place on a "Crossover Earth", but later intercompany crossovers tended to present the DC and Marvel Universes as alternate realities, bridged when common foes made this desirable. (The interest in overall continuity has become a major part of even crossover comic books.)
Characters are often licensed or sold from one company to another, as with DC acquiring such characters of Fawcett Comics, Quality Comics, and Charlton Comics as the original Captain Marvel, Plastic Man and Captain Atom. In this way, heroes originally published by different companies can become part of the same fictional universe, and interactions between such characters are no longer considered intercompany crossovers.
Although a meeting between a licensed character and a wholly owned character (e.g., between Red Sonja and Spider-Man, or Ash Williams and the Marvel Zombies) is technically an intercompany crossover, comics companies rarely bill them as such. Likewise is the case when some characters in an on-going series are owned or to some extent controlled by their creators, as with Doctor Who antagonists the Daleks, which are not owned by the UK television network the BBC although the character of The Doctor is.
Other articles related to "intercompany crossover, crossover":
... Crossover Classics The Marvel/DC Collection Vol ... the Incredible Hulk, The Uncanny X-Men/The New Teen Titans) DC/Marvel Crossover Classics II (collects Batman/Punisher Lake of Fire, Punisher/Batman Deadly Knights, Silver Surfer/Superman, Batman and ... Daredevil/Batman) DC/Marvel Crossover Classics IV (collects Batman/Spider-Man, Superman/Fantastic Four, Green Lantern/Silver Surfer, Darkseid vs ...