Canon Invasion

Canon Invasion is when two unrelated titles are originally owned by two different entities but are forced into the same fictional universe after one buys the rights from the other. Sometimes, it's immediately after; other times, it's Canon Welding belatedly kicking in.

The "Invaders" bring their own, possibly conflicting, continuity with them; and since they didn't originate with the same creator, the differences will likely be more severe than with Canon Welding. Expect Retcons, especially if the invaders are inserted directly.

Because of the Continuity issues, Canon Invasion may turn The Verse into The Multiverse as its first effect (if the original 'verse wasn't already a multiverse), especially if there are huge differences in the laws of metaphysics. The original canon characters are in one universe, and the newer ones in another, and now there is a bridge between them. Thus, Canon Invasion is sometimes less disruptive than Canon Welding.

Comic Books

 * In The DCU:
 * Going back to The Golden Age of Comic Books, even characters such as Superman, Batman and Wonder Woman were initially not thought of as being part of the same continuity.
 * The Question, Blue Beetle, Captain Atom and others started out in Charlton Comics before being sold to DC Comics. In fact, Watchmen was going to use them as its characters, except DC actually wanted to be able to use them again later. Hence the team of Captain Ersatzes instead.
 * The same goes for the Fawcett characters (the Shazam! Captain Marvel and the Marvel Family), and the Quality Comics characters (Plastic Man, the Blackhawks and the Freedom Fighters (the rest are Public Domain Characters))
 * They did this again with the Red Circle - a series of one-shots that brought old Archie Comics superheroes the Hangman, Inferno, Shield and Web into The DCU. Unlike the above examples, DC didn't buy the Red Circle characters - it merely licensed them for a few years.
 * This has now been done again, the difference being that the characters are now brought into DC's mainstream universe.
 * Dc's back to not referencing them due to Archie getting the rights back and because of the Reboot.
 * Milestone Media, the creators of the Milestone Comics line (including Static), originally had them published via DC Comics, but as their own distinct universe. DC eventually struck a deal with Milestone to bring the characters into the DCU proper, as well as the Static Shock TV show getting pushed into The DCAU.
 * The Wildstorm Comics universe. Originally part of a loosely-defined Image Comics universe, Wildstorm was integrated into the DCU Multiverse as "Earth-50" with a series of crossovers involving Superman, Majestic, and Captain Atom.
 * And now the new DC reboot is bringing Wildstorm into The DCU as well.
 * In the Marvel Universe:
 * Although technically always owned by the same company, the Eternals at Marvel is otherwise an example. The series was created by Jack Kirby as separate from the Marvel Universe, but later brought into it, with the result that, for instance, there would be Marvel Universe versions of gods but Eternals who were posing as those same gods.
 * This was lampshaded in an issue of The Mighty Thor where it was revealed The Eternals and The Olympians had made a pact so the former would "represent" the latter in front of mortals.
 * Also Machine Man originally appeared in issue #8 of Kirby's monthly comic of 2001 A Space Odyssey where each issue a different person encounters the 2001 monolith. Machine Man later got his own series and was integrated into the Marvel Universe.
 * Many references from movie were rewritten away. However, it is sporadically mentioned that the creators of the monoliths were.
 * Marvel bought out Malibu Comics in 1994 and soon Marvel heroes and villains were cropping up in Malibu titles. However, Marvel soon canceled all of the Malibu titles and common fan speculation was that Marvel only bought the company to acquire Malibu's then-groundbreaking in-house coloring studio, and/or its catalog of easily movie-licensed properties. Within the Marvel Comics multi-verse, the Malibu Universe is now designated as Earth-93060.
 * Believe it or not, when Marvel briefly had the rights to publish Godzilla comics, Big G himself was a character in the Marvel Universe.
 * And it's still considered 616 canon!
 * Even though ROM Spaceknight can't be referenced, all the supporting characters and villians can still be seen in comics and the series is still canon.
 * Aside from actually calling the Micronauts, the Micronauts all the characters created for the comic can still be used and are all canon. Hell the character Bug is a member of the Guardians of the Galaxy and Captain Universe nearly killed Juggernaut in a recent Spider-Man comic.
 * While ignored later on, Spider-Man appeared in early issues of Marvel's Transformers series, which made the Autobots and Decepticons Canon Immigrants to the Marvel Universe, at least temporarily.
 * Technically the Marvel Transformers comics took place on alternate universes (Earth-91274 for the American comics and Earth-120185 for the UK comics) and are a huge part of the character Death's Head origin, so the Transformers comics are very loosely canon.
 * But don't ask where Earthforce fits in as not even Marvel or Hasbro will attempt to make it canon. These are the company's where Marvel What Th--?! and Transformers: Kiss Players are to some degree canon.
 * Don't forget that Evil Dead fits in here as the Dynamite Army of Darkness comics got referenced in the Marvel Zombies crossover and numbered in an issue of The Offical Handbook to the Marvel Universe.
 * Doctor Who is somewhat canon if only because the Doctor has crossed over with Death's Head, Marvel's version of Merlin, and the obscure Special Executive (who first appeared in Doctor Who #51).
 * Licensed Robert E. Howard characters are probably the most firmly fit into the Marvel Universe. For example Conan (major enemy of Kulan Gath, enemy of Set a serpent god who powers the Serpent Crown, and ally to Red Sonja who would crossover with Spider-man twice), King Kull (who ruled over Namor's Atlantis in pre-history), and Solomon Kane (appearing in back up stories in Savage Sword of Conan, as well as getting his own mini-series.)
 * Shuma-Gorath was also an enemy of Conan's god Crom.
 * Fu Manchu is Shang-chi's dad. That is all.
 * U.S. 1 is canon to the Marvel Universe.
 * Marvel's Guardians of the Galaxy/Killraven continuity entire premise is that after the Martians of War of the Worlds failed to conquer Earth the first time, came back in 2001, and basically killed almost every super hero with only freedom fighters left to defend Earth.
 * Earth-7642 of the Marvel Multiverse is a universe where all the crossovers that act as if characters crossing over with Marvel where part of continuity the entire time. It consists of most of the 70's to 90's crossovers with DC Comics, the IDW version of Transformers, Shi, Painkiller, many Image Comics and Top Cow characters, Archie Comics, and a few Wildstorm characters.
 * Subverted in the case of the Marvel Doc Savage comics, which didn't last long and the only proof of Doc existing in Earth-616 is him crossing over with the Thing and Spider-Man.
 * Valiant Comics continuity was made up of original characters and licensed 1960s characters that were originally published by Gold Key Comics. Furthermore, the licensed characters, which originally existed in separate continuities, were retroactively linked together, forming the basis for the rest of the shared continuity.
 * 2000 AD absorbed a similar SF based comic called Starlord in the 1980s. The only Starlord strips that stuck were Strontium Dog and Ro-Busters. The backstory of Strontium Dog has been absorbed into the same continuity as other 2000AD strips and there have been crossovers with Judge Dredd, even though it happens after a nuclear war which is yet to occur in Dredd's universe.
 * The short-lived Semic Comics universe took characters from two different French publishers and combined them all into a single integrated continuity, which is quite a feat considering almost all the characters involved were originally unrelated to each other.
 * Several non-player characters in the Global Guardians PBEM Universe are direct lifts from DC and Marvel Comics, including Hawk, Dove, Cloak, Dagger, and Uncle Sam.

Tabletop Games

 * Palladium Books is best known for their flagship line, Rifts, but they also have the license to produce the Robotech RPG. This one is used inconsistently; Robotech is canonically in the Megaverse, and there are rules (down to technical specifications) for crossing Robotech characters and mecha over into Rifts, but it hasn't actually happened in official material.