Canon Welding

"They were independent, separate stories. But now... the stories are combining, that's why the worlds are becoming one."

— Wataru Kurenai, Kamen Rider Decade

When an author or creator takes two previously unrelated works and puts them into a single, shared continuity.

Sci-fi and fantasy authors don't always write all their novels in the same continuity. A budding new author's first published book might be about space pirates in the 27th century, while his sophomore effort might instead be about 21st century scientists reverse-engineering a flying saucer. In response to popular demand, he might end up writing a sequel to one, or even both of these novels.

Some years later, the author decides that all their works were set in one contiguous world (or something between "country" and "universe"), perhaps in different times or places, perhaps close enough for the characters to meet. Maybe their storytelling ambitions have grown to expand their work into a grand tapestry of fictional history. Maybe connecting the franchises in a bigger one will be a lucrative prospect for them or their works' later owners. Maybe they're creatively spent and bashing their old works together will wring out a few more releases?

Many long-lived genre authors tend to resort to Canon Welding, usually at a later point in their career. They combine two or more distinct series they've created into a single continuity. This isn't just a one-off Crossover; for series with radically different premises, the foundations of one or both stories can be altered forever.

By combining the two series together, the author can introduce fans of one series to characters they may not be familiar with, inducing them to go out and buy the works in that series, and hopefully attract high sales from fans of both storylines. When done well, it can add a more epic feel to the tale, explore aspects of the two storylines not previously delved into, and make lots of money for the author and his publisher (and there are many examples of this, perhaps most famously The Lord of the Rings). When done poorly, especially with stories with radically different settings or styles, it looks and feels like a shallow money-grab and can potentially be a shark-jumping moment for both series.

Modular Franchise is when it's done at a corporate level. When this is done by fans, it becomes either a Patchwork Fic if all of the components are part of a single Franchise or one variety of Fusion Fic if they are not. Crossover Relatives is often used as part of the weld, both at the individual level, by creating a familial relationship between notable characters, and at the group level, such as by establishing similar fantasy or alien species from the fused works as descending from each other or from a common root stock. Compare Shared Universe, which can be created through Canon Welding if it wasn't shared from the beginning. See also Character Overlap.

Supertrope to Public Domain Canon Welding, which is for when at least one of the works is Public Domain. For the fanon equivalent of this trope, see Fanon Welding. Not to be confused with welding artillery.

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Example Subpages:

• Cross-Media
• Literature
• Video Games

Other Examples:

Anime & Manga

• Manga creator Go Nagai does this often with his various works, although Mazinger Z and UFO Robo Grendizer were already part of one continuity from Grendizer's get-go.
  • Shin Mazinger is quickly reaching a critical level of this, with a woman from Violence Jack turning out to be Kouji Kabuto's mother.
  • Violence Jack has incorporated Devilman and later Devilman Lady as taking place in one Universe that resets itself and all main characters are really incarnations of Akira Fudou. And because the series is also Deconstructor Fleet for all other Go Nagai's manga, there are many theories incorporating them into it in all incarnations, which is possible thanks to the nature of this world. Cameos and crossovers between his works are so often it's pretty easy. Then there's Devilman Grimoire, where Jun Fudo and Aoi Kurosaki from Devilman Lady are shown to be teachers at Akira and Miki's school. They are also lovers. Alphonse and Himura, from the 1970s Devilman anime series, also feature.
• Gosho Aoyama's three main works Case Closed, Magic Kaito, and Yaiba!, have the tendency to merge into one universe. Magic Kaito was more or less put on hold in favor of Case Closed, but its characters occur so frequently in Case Closed to be the latter's recurring characters. Although, Aoyama also drew the line: Case Closed does not deal with Magic Kaito characters in their civvies.
  • Aoyama later tried to backtrack in at least one Q&A and claim that the Kaitou Kid who shows up every fifty chapters or so in Case Closed is a "parallel" version to the one in Magic Kaito. Very few fans take him seriously on this (as both Kid and his predecessor have played distinct roles in Conan's Myth Arc), and ninety-nine percent of fanfiction (e.g. "When Pandora's Box Is Opened") take the two 'verses being one for granted.
• The Gundam franchise started off with only the Universal Century timeline under the auspices of creator Yoshiyuki Tomino. When he stepped away from the franchise in 1993, Sunrise introduced the concept of Alternate Universes to allow new creators to explore their vision of Gundam without creating a Continuity Snarl, resulting in the Future Century, After Colony, and After War timelines. Then Tomino returned for the 20th anniversary and created ∀ Gundam, set in the Correct Century timeline, which was eventually revealed to be the Distant Finale of all of Gundam, including the AUs, although this involves a lot of Continuity Snarl regarding the timelines. Tomino's latest work, Gundam: Reconguista in G, takes place in the Regild Century timeline, which is explicitly stated in-series as being the era that came after the end of the Universal Century. Additionally, the non-canon manga Gundam vs. Ideon: Counterattack of Gigantis reveals that the Universal Century timeline was the new universe created after the destruction of the previous universe at the end of Space Runaway Ideon, another Tomino series.
  • The anime Gundam Build Fighters, also plays into this, which takes place in a 20 Minutes into the Future setting where Gundam is a popular anime franchise. Presumably the same applies to Model Suit Gunpla Builders Beginning G, which is Build Fighters' spiritual precursor.
• The mangaka group CLAMP has been known for self-crossovers for many years, but their twin series Tsubasa -RESERVoir CHRoNiCLE- and ×××HOLiC are meant to tie all their works—both present-day and fantasy—into a single continuity.
• Pretty Cure All Stars. 14 magical girls from 4 different continuities save the day. Awesome.
  • The second All Stars-movie features 17 magical girls from 5 different continuities. From the previews it seems to feature some of the different baddies, too.
    • All Stars DX 3 ups the number to 21 from 6 continuities and the brand-new New Stage brings it to a grand total of 28 from 7. It overlaps with Remember the New Guy? as a lot of Cures that show up in one movie weren't in the movie before that.
    • All Stars New Stage delivers a Retcon of sorts now stating that 23 magical girls from 6 different continuities saved the day. Then 5 more from the 7th hopped in and it was madness.
  • Interestingly, it seems that Smile PreCure! is attempting a bit of a Canon Weld experiment themselves - an episode midway through reveals that Yayoi's mother works for Fairy Drop, the store owned by Erika Kurumi's mother. And said mother is mentioned, at least by last name.
• Eiichiro Oda re-used Ryuuma, a character from his one-shot manga Monsters, as a (zombified) villain in One Piece and his home country was mentioned to be part of the New World (the second half of the Grand Line). He later confirmed that Monsters was incorporated into the backstory of the setting.
• Negima! Magister Negi Magi reveals that all of Ken Akamatsu's major works exist in the same universe. The ties between Negima and Love Hina are obvious with Setsuna being a Shinmeiryuu swordswoman, which is lead by the Aoyama family from Love Hina; the reference to A.I. Love You is found in a single panel, although it's kinda important, as the protagonist of that series is implied to have written the code that enables Chachamaru to have a soul.
• Dragon Ball:
  • Before he gave the world Dragon Ball, Akira Toriyama's first popular series was a comedy called Doctor Slump, about a robot girl and the slob scientist who created her causing havoc in a weird place called Penguin Village. About a year into the Dragon Ball series, Toriyama had Goku visit Penguin Village and meet most of the Slump cast, thus joining the two series into one universe. This was mostly done as an attempt to use Dr. Slump's popularity to help increase readership of Dragon Ball, as it wasn't the huge hit it would eventually become yet. In contrast, the crossover has had the opposite effect in later years: many fans, especially outside of Japan, only know the Dr. Slump cast because of their guest spot on Dragon Ball. It's gotten to the point that Arale's made it into at least three Dragon Ball video games as a playable character! Dragon Ball Z: Budokai Tenkaichi 3, Dragon Ball Origins and Revenge of King Piccolo, to be precise. The first one also caused a good amount of rejoicing for those who knew her.
  • The Akira Toriyama manga Pola and Roid, Tomato, Girl Detective and Wonder Island connect to Dr. Slump through cameos. The manga Dub and Peter 1, Escape, Go! Go! Ackman, Kajika, Kintoki, Nekomajin/Nekomajin Z, and Sand Land might all take place in the Dragon Ball universe (Galactic Patrol of Jaco the Galactic Patrolman, Jiya and Sachie-chan Guu!! fame is confirmed to take place due to its ending).
  • Dragon Ball Super is an odd example, since while it's specifically meant to be a sequel to the original Dragon Ball manga rather than the anime, various anime-only Filler moments get directly referenced. Gregory, an anime-only character, is present, Android 18 gets pissed when 17 accidentally calls Marron "Maron", Krillin's girlfriend from the Garlic Jr. filler arc of Dragon Ball Z, and when Krillin is surrounded by ghosts of the various villains they've fought over the series, Captain Ginyu in Bulma's body also appears, something that also never happened in the manga. On the other hand, Gohan at one point talks to a group of bus hijackers he stopped in the manga, but not the anime, and various continuity errors, such as the different depictions of hell in the Z anime and Super exist if one tries to connect them directly.
    • That is probably not Ginyu in Bulma’s body. Krillin commented that he finds Bulma scarier than Frieza.
• Leiji Matsumoto is notorious for this, with Galaxy Express 999, Captain Harlock, Queen Millennia, and Space Battleship Yamato crossing over to various degrees, not always following a consistent continuity.
• Endings of Getter Robo Armageddon and New Getter Robo in which Armageddon versions of Ryoma, Hayato and Benkei and New version of Ryoma ends in Warrior Heaven, alongside countless Getters, fighting unknown monsters has hinted that all Getter's separated continuities (two mentioned above, Ken Ishikawa's manga continuity, Getter Robo DASH manga and anime Getter Robo Go and Shin Getter Robo Vs Neo Getter Robo) might exist in the same Multiverse.
• Madhouse Studios anime adaptations of four Marvel Comics' titles - X-Men, Iron Man, Wolverine and Blade - are set in one Universe, confirmed both by Word of God from Marvel and the same Wolverine appearing in all four anime.
• GaoGaiGar FINAL has blink-and-you'll-miss-it cameos of characters from Betterman, establishing those two series takes place in one Universe.
• REDLINE does this by making main characters from two different anime - Miki and Todoroki from Mole Brothers and Trava and Shinkai from Trava First Planet - participating in the eponymous race.
• Several years ago, Hidenori Kusaka and Satoshi Yamamoto worked on a short Pokémon Ranger manga that was only released online. As it turns out in the Platinum arc of Pokémon Adventures, the events that occured in that online comic are indeed canonical. The Ranger story was later included in an Adventures art book.
• Time Bokan:
  • Yatterman Night has the cast encountering characters (or in some case, blatant Expies) from various other shows produced by Tatsunoko Production. One episode even has Galina and Alouette driving the Mach 5!
  • This seems to be tradition for Yatterman: the original and 2008 series crossed over with several Tatsunoko shows, and even placed them in a "Tatsunoko Kingdom" where all Tatsunoko characters appeared to reside in during one OVA.
• Makoto Shinkai's films The Garden of Words, Your Name, and Weathering With You have been confirmed to exist in the same timeline thanks to various character crossovers. Yukari Yukino shows up as the English teacher at Itomori High School in Your Name while Taki, Mitsuha , Saya, Teshi, and Yotsuha have cameos in Weathering With You.
• Eiji Ohtsuka has demonstrated that his horror manga MPD Psycho and The Kurosagi Corpse Delivery Service share a continuity thanks to the character Sasayama, who appears as a police officer in the former and as a social worker, at a later stage of his life, in the latter.
• Before High School D×D, Ishibumi wrote the first iteration of SLASHDØG which flopped and never went past the first volume. However, he did bring in Tobio Ikuse first as a Canon Immigrant in Volume 15 in 2013, a year later he went and rewrote SLASHDØG and properly placed it in the same universe as DxD, bringing along Grauzauberer and Akeno's extended family and properly developed it into The 'Verse by adding a character from his first and most obscure work, Denpachi.
• City Hunter: Shinjuku Private Eyes confirms that the series exists in the same universe as Cat's Eye, with the three Kisugi sisters turning out to be the true owners of the cafe that Umibozu and Miki run.
• Tohru Fujisawa, best known for Great Teacher Onizuka, confirmed several of his other series, Kamen Teacher and Animal Joe, exist in the same universe as GTO, with the main characters making cameos in GTO: Paradise Lost. He also wrote a crossover between Kamen Teacher and Ino-Head Gargoyle, a spinoff of GTO.
• The original Ghost in the Shell and Appleseed mangas are said to be set in the same timeline but don't reference any of each other's characters or events. About the only thing they share is some of the Space Filling Empires, notably that North America is now dominated by the Divided States of America after several more world wars.
• Ayakashi Triangle eventually established Yamato Gensouki (Kentaro Yabuki's first serialization) as events that occurred in the distant past, at least in Broad Strokes. A flashback uses the same design for Empress Iyo, who is Suzu and the ayakashi medium's earliest past life. It has elements of Fully Absorbed Finale, partially resolving the plotline Cut Short in Yamato Gensouki: Iyo's power came from being a human incarnation of the goddess Amaterasu. The Onmyoren, the story's villainous organization, failed to conquer Japan but still exists as the Gogyosen, who founded and have authority over the Exorcist Ninja Association.

Comic Books

• The DC and Marvel universes were born from this trope; originally, the titles published by each company did not overlap, but over time, cameos, Crossovers, and inside references combined to form the comic books into one big, interconnected web. That's not even counting the Amalgam universe. Since DC vs. Marvel in 1996, it's revealed all crossovers were canonical — more or less. ^note The different universes and realities occasionally touch, causing them. Access' job is to make sure they don't stick.
  • Mind you, Marvel started this with the first issue of Spider-Man. And even before that, Marvel started this 21 years earlier in the Timely Comics era, when Human Torch faced off against Namor the Sub-Mariner for the first time. They teamed a few more times over the next few years, and some of the less prominent characters occasionally got involved. Then, in 1946, Timely launched the All-Winners Squad, teaming up existing characters like Captain America, the Human Torch, and the Sub-Mariner (among others).
  • DC started it in All-Star Comics #3 with the Justice Society's first meeting. To this day, it's generally accepted that the Justice Society is the first-ever example of a super hero team lasting longer than a single issue in comics history.
  • DC has also historically made a habit of assimilating the characters of other comics companies into their multiverse - Quality Comics (Uncle Sam and the Freedom Fighters, Plastic Man, Blackhawk), Fawcett Comics (Shazam, Captain Marvel and the Marvel Family), Charlton Comics (Captain Atom, Blue Beetle, The Question), Wild Storm (The Authority, Wild CATS Wild Storm), Milestone Comics (Icon, Hardware, Static) and Archie Comics' Red Circle superhero characters. Generally, these characters start off in alternate universes, and then some sort of universal crisis reboots the DC Universe yet again, merging the universes. That said, sometimes the welding isn't permanent, as with the Red Circle characters, who eventually returned to Archie.
  • DC Rebirth saw the welding of Watchmen and the DC multiverse.
  • Interestingly, it's suggested that they are all interconnected through... X-Men: The Animated Series. The final issue to the 1996 comic series X-Men Adventures, which is set in that animated universe, revealed that universe was the universe that gave way to the main Marvel Universe (thus making Galactus a Canon Immigrant retroactively). Even more, the Living Tribunal is shown watching the creation of this world, temporarily holding back the brothers who would cause the aforementioned DC vs. Marvel event and even mentions needing to talk to his his hooded spectorial counterpart.
• Shazam! and Kid Eternity are a particularly interesting example. DC acquired the rights to both from separate comic companies. Eventually, they realized that Shazam's Freddy Freeman and the nameless Kid had remarkably similar back stories—both were raised by a grandfather who died in a boating accident caused by Nazis, which also resulted in the grandson getting superpowers activated by saying a magic phrase. As a result, Freddy and "Kit Freeman" were revealed to be brothers.
• Jack Kirby's The Eternals clearly took place in a separate continuity at first, but later writers integrated the characters (most notably the Celestials) into the wider Marvel Universe.
• Image Comics is an interesting case.
  • Originally, all of its titles took place in a shared universe. Over time, the original Image partners focused on their own corners of the Image Universe, causing the continuity to split into several distinct sub-continuities. The Shattered Image crossover made the split official. But Image partners still occasionally "borrowed" each others' characters, so the sub-universes still interacted. As new, non-partner creators become more prominent in Image Comics, they started building universes of their own, and they occasionally used the Image partners' characters. For example:
  • Characters from Jay Faerber's creator-owned series (Noble Causes, Venture, Firebirds, and Dynamo5) appear in each other's books all the time, creating a loose-knit "Faerberverse".
  • Robert Kirkman's characters occasionally cross over in a similar fashion (and sometimes become supporting cast - especially in Invincible). The Kirkmanverse and Faerberverse intersect at a number of points, especially The Pact mini-series. Other Image characters, such as Savage Dragon and Shadowhawk, often pop up. Spawn didn't make an appearance until Image United, which brought together characters of all of the current Image partners (Erik Larsen, Rob Liefeld, Todd McFarlane, Marc Silvestri, Robert Kirkman, and Jim Valentino), as well as Whilce Portacio and several other creators.
  • Angela from the Spawn universe jumped ship to the Marvel Universe at the close of Age of Ultron.
• Eclipse Comics' four-part crossover mini-series Total Eclipse brought together virtually all company-owned and creator-owned characters that the company published.
• 2000 AD:
  • The Harlem Heroes strip (about a basketball team with jetpacks in 2050) appeared to be totally unconnected to the 22nd centuy of the Judge Dredd universe until the son of one of the Heroes (John "Giant" Clay) joined the Judges (as Judge Giant).
  • The Judge Dredd story "Hammerstein" suggested ABC Warriors was also set in the past of the Dreddverse, but later ABC Warriors stories contradicted this.
  • Judge Dredd has also had crossovers with other 2000 AD strips whenever the writers felt like it, most notably Strontium Dog and the story Helter Skelter (where Garth Ennis basically crossed ALL his favourite strips over with Dredd).
  • Meanwhile, 2000 AD stalwart Pat Mills has crossed over everything he's ever written for 2000 AD with each other. Invasion!/Savage, Flesh, Ro-Busters, ABC Warriors, and Nemesis the Warlock all slot together.
  • Ian Edginton does the same thing with his 2000 AD strips: both Stickleback and The Red Seas share a secret organisation, little mentions and character cameos abound, and the same brand of monster appears in Stickleback, Ampney Crucis Investigates, and Detonator X.
  • Even more Edginton crossovers: Sir William Ashbless, immortal designer of the titular ship in Leviathan made a cameo appearance in Stickleback and his shipping company, White Hart Line, got name dropped in Ampney Crucis Investigates. Also a few locations have been repeated across the various strips at different periods in history.
  • John Smith did a similar thing from the start in order to make his stories stand out: all his initial Future Shocks linked in to an organisation called Indigo Prime, and a couple of Indigo Prime agents also appeared in Tyranny Rex. Indigo Prime then got its own series, and eventually crossed over with Smith's Vertigo Comics series, Scarab.
• Alan Moore:
  • He, as time has gone on, has turned The League of Extraordinary Gentlemen into this, making vague references to the source material for Ozymandias and The Black Freighter. Oh, sure, it's only references to the inspirations for them, and Moore would probably rather have his skin boiled than actually go further than that, but this is Alan Moore. There are no coincidences. As an aside, Moore is a close friend to Moorcock, close enough that Moorcock has allowed Moore to put in some Moorcock characters into the League series free of charge.
  • Back in the day, Alan Moore sketched out a unified Warrior timeline, the most notable aspect of which was that, in an Alternate Universe where Micky Moran never regained his memories and powers, Emil Gargunza went on to build Fate, Norsefire's supercomputer. The timeline also established when all the "centuries in the future" strips happened in relation to each other, and introduced the Chronarchs, who Moore calls "Earth-2 Time Lords", and who seem to be based at least partly on his own version of Gallifrey in the Doctor Who Magazine comic strip. Then Moore quit Warrior and the book collapsed before any of this could actually appear.
  • Moore's Providence is an attempt to do this for all of H. P. Lovecraft's stories, or at least the different cycles. Much like League of Extraordinary Gentlemen, Moore is using Lovecraft's fiction to merge different stories and events into a single coherent verse. This includes "Cool Air", "The Horror at Red Hook", "The Shadow Over Innsmouth", "The Dunwich Horror", "The Colour Out of Space", "The Dreams in the Witch House", "The Thing on the Doorstep".
• Frank Miller's Batman stories: Batman: The Dark Knight Returns, Batman: Year One, The Dark Knight Strikes Again, and All-Star Batman and Robin were originally supposed to be in separate universes, with only Batman: The Dark Knight Returns and The Dark Knight Strikes Again having any clear continuity with each other.
• This article suggests that all of Mark Millar's later Marvel works (1985, Fantastic Four, Kick-Ass, and Old Man Logan) is all interconnected. (Three of those are automatically canonical to each other anyway, of course, but Kick-Ass is more of a surprise.) Even earlier Millar established connections between three comics published by different companies - Wanted, Chosen and The Unfunnies. The reason why at the end of Chosen the media doesn't report the Antichrist's miracles is that they're controlled by supervillains from Wanted. And Troy Hicks from Unfunnies helped Satan rape the Antichrist. Never published Run! was supposed to be set in that world too.
• Grant Morrison's All-Star Superman and DC One Million seemed to be tied in the same continuity.
  • Of course, Grant Morrison is one of the architects of Hypertime (the other being Mark Waid) which posits that it is all true. Under this concept, the events of DC vs. Marvel exist somewhere in continuity.
  • Almost all of Morrison's DC works are tied to each other, as well to the real world, forming a big "Morrisonverse". Here's how it goes: In All-Star Superman Superman creates the infant universe Qwewq. In JLA we see the heroes discover (a version of) Qwewq. Both in ASS and in JLA: Confidential we see that Qwewq actually contains "our" Earth, i.e. a realistic Earth with no superheroes. The final Morrison-penned issues of Doom Patrol and Animal Man take place in a realistic world with no superheroes (and they both share the same colour scheme, meaning it's the same world in both), which is presumably Qwewq, i.e. "our" world. In Seven Soldiers we find out the ultimate fate of Qwewq (or at least one version of it). Final Crisis (which takes place in the same universe as JLA) refers to Bleed (the "sea" that separates different universes in the DC multiverse) as "ultramenstruum", and the same term is used is The Invisibles, implying that the Invisibles universe is a part of the larger DC multiverse. If we accept that Qwewq is "our" universe, this means our universe exists inside a larger universe populated by superheroes. Both Flex Mentallo and The Filth feature the "real" world to which superheroes from outside this world burst in; thus, the real world in both these comics could be (a version of) Qwewq. And then a huge chunk of the Damian Wayne stories written by Morrison that take place in the not too distant future were revealed to be set in the past of DC One Million and ends with Damian training Terry McGinnis from Batman Beyond to become his successor. Lastly it also seems that DC One Million takes place in the future of All Star Superman as Solaris and Kal Kent appear and happens to be the story of how Superman ended up having to fix the sun. To sum it up, almost all of Morrison's major works for DC are welded together, though admittedly some of the links between them are vague.
• When Semic Comics, a French comic publisher, decided to revive the characters it inherited from defunct Editions Lug, editor Jean-Marc Lofficier set out to link over 2000 largely unrelated characters from just about every comic book genre into a single continuity. Some characters had to be revamped fairly drastically to fit in, and a few had to be revamped to avoid duplication.
• In Non Sequitur, Wiley frequently used four separate sets of recurring, originally nameless, characters: a silent Everyman who'd observe some of the comics' less absurdist strips, a Leisure Suit Larry-ish barfly, a snarky Bratty Half-Pint girl and the Sunday-only diner owner "Offshore" Flo (and her tall-tale telling patron, Eddie). Gradually, the characters started interacting: the Everyman and the barfly were seen hanging out at the bar, the girl and Flo would occasionally be seen reacting to something from the Everyman's radio talk show. Eventually, Wiley brought all these elements together to form a central core: Joe (the everyman) and Bob (the barfly) are brothers, Danae (the little girl) and her little sister are Joe's daughters and Flo is Joe and Bob's mother. Eddie remains "just" Eddie.
• In one Super Special Sonic the Hedgehog (Archie Comics), Sonic finds himself universe hopping to the Sonic Underground universe. In the 25 Years Later storyline, he names his children after his counterpart's siblings.
  • In the same Super Special, Sonic and Sally end up universe hopping again and teaming up with Sabrina the Teenage Witch, making the Sonic comics part of the Archie Comics multiverse, not just under their label.
  • In another, the Freedom Fighters universe hop into the Image Comics universe, meeting Spawn, Savage Dragon, the Maxx, and Shadow Hawk.
  • The Mega Man comic started being welded into the Sonic comic canon as well.
• Asterix: The villain of Asterix and the Magic Carpet briefly refers to his cousin Iznogoud.
• One issue of PS238 reveals that it and Nodwick are set in the same world, though taking place in different "Heroic Ages".
• 2017's The Scream and Misty Special did this in a couple of strips. Maxine in The Return of Black Max passes by the Sentinels from The Return of the Sentinels, and the title character of Death-Man encounters aged versions of classic Fleetway characters Leopard from Lime Steet, Pete's Pocket Army, Deathwish, Steel Commando, Paddy McGinty's Goat, Doctor von Hoffman, the Iron Major, and The Dwarf, as well as the successors of Doctor Sin and Thunderbolt the Avenger.
• This is the crux of the plot for RoboCop Versus The Terminator: the technology that turned Alex Murphy into RoboCop leads to Skynet gaining sentience and the creation of the Terminators.
• Street Fighter vs. Darkstalkers establishes that the cast of both series shares the same continuity. For instance, Kolin is revealed to have gained her powers after slaying an ice werewolf.
• Garth Ennis' characters seem to coexist in a single unified verse, with characters from Hitman (1993) being referenced in The Punisher MAX or Cassidy from Preacher showing up in The Boys.
  • His run on The Punisher can be divided into two 'verses: the Marvel Knights one set after the "Angel Punisher" Audience-Alienating Era where superheroes exist and regularly get in Frank's way, and the MAX universe that's basically our world but crappier (superheroes don't seem to exist and Nick Fury is an operative who started in WW 2 with no explanation for why he never ages). However, characters from the first verse (Jen Cooke, Yorkie Mitchell and the Russian) made appearances in the MAX continuity.
• IDW Publishing's GoBots miniseries ends with heavy implications that the GoBots are actually precursors to Transformers. In particular, Road Ranger talks of creating an heir who is an "optimized" version of himself and encourages Bug Bite to do the same, which implies that they are the creators of Optimus Prime and Bumblebee. The two also decide to recycle Leader-1 and Cy-Kill's remains to create a new GoBot, who is seen undergoing construction in the form of a jet plane similar to the alt mode of the Decepticon Starscream.
• Radiant Black launched in 2021 as its own title that occasionally had its lead characters, who are comic book fans, make reference to C.O.W.L., another comic by Kyle Higgins. However, it was made clear that other superpowered beings did not exist in the universe, as the characters have nobody for guidance in relation to their powers. Later on, Supermassive officially launched the universe, the Massive-Verse, introducing characters Rogue Sun and Inferno Girl Red. Despite this being its official launch, the events of C.O.W.L. were retroactively incorporated into the universe as well.

Fan Works

• Haunted Mansion and the Hatbox Ghost: The fanverse includes several properties (fanmade and official alike) welded together into a single continuity, even when no continuity was intended from the authors.

• Infinity Train: Star Finder: Subverted. The events of Infinity Train: Blossoming Trail still happened on this continuity, but with many changes and into a Broad Strokes fashion. Chloe became the unown wielder and boarded the train after the mess she caused, but she kicked the bucket during a mission with her partner Kirby.

• Marooned in Madagascar: Subverted. The movies, The Penguins of Madagascar and All Hail King Julien are shown to be in the same universe but represent alternate timelines, with the latter being the most disconnected from the rest, as this King Julien has no intentions of abandoning his kingdom and is gobsmacked that any version of himself would do it. The Penguins of Madagascar is shown to be canon with the first two movies, but it and the third one represent branching timelines, where in the former, Julien, Maurice, and Mort sailed to New York on their own, while in the latter, they joined the Zoosters on their trip to Europe.
• "Of Powers and Pie" combines Pushing Daisies with Heroes by making Ned’s ability one of the many superpowers manifested in the show; later in the fic, Ned learns that he can use his ability to also heal the injured, healing Elle of serious injuries when she’s crushed by a collapsed ceiling and mending Mohinder’s broken leg. As well as Ned, Olive realises that she can create force-fields when she is attacked by Sylar before Peter Petrelli saves her.

• The fanfic Spider-Ninja specifically states that it's story takes place in a part of the Spider-Verse where a Gender Flipped Peter Parker was adopted by Master Splinter after her birth family was killed. The story technically does this trope to both franchises, as Petra Parker (while getting her powers the same way Peter Parker did) lives a completely different life from most Spider-Man incarnations. Similarly, the story welds together the 2003 series (using the same locations and characterizations) and the 1987 series (Splinter is the mutated Hamato Yoshi and April is a reporter).
  • Also, Dr. Curt Connors went to college with Doctors Baxter Stockman and Otto Octavius.
• Ice Fury specifically states that the events of this crossover were set in motion when Elsa's eternal winter caused the events of the Dragons: Riders of Berk episode "Frozen" (when Berk experienced such an intense winter that the ocean froze and they were attacked by the grounded Speed Stingers). When Elsa meets Valka, it is explained that the archipelago where Berk and the other depicted islands exists is isolated from the wider world, justifying the continued existence of Vikings when Frozen was implied to be set in the 1800s.
• The Slayer Prophecy has a few of these, mostly explaining how the Buffy cast can be part of the wider DC Universe and still have spent so long acting alone;
  • It is explicitly stated that the Hellmouth deflects external interest, which is why none of the major superheroes of the DC Universe have visited the city before.
  • Rack apparently fought Doctor Fate in the past before Rack and Fate disappeared from the public view.
  • Spike observes that Dala and the Monk were members of the Order of Aurelius, with the Monk just a little bit younger than the Master was at the time of his death.
• In Harry Potter and the Mystic Force, it is established that Harry Potter and Power Rangers exist in the same universe (and in a reality where the Rangers battled Ivan Ooze as well as apparently all other televised continuity still being valid); no reference is made to other Hogwarts students being aware of past Rangers, but this can be attributed to the wizarding world’s stereotypical ignorance of muggle activities.
• In Tara Sheppard, after Tara McClay meets her half-brother John Sheppard and learns about his work with the SGC, after analysis of Tara's DNA provides the means for the Asgard to cure their genetic degradation, Thor provides a full history of how demons fit into what the SGC know of Earth’s history.
• Finmonster's The Marvelous World Of DC and its sequel, Harry Potter and the Guardian's Light has an abundance of this;
  • Krypton is destroyed by Galactus, and Kal-El's landing is investigated by the Men In Black (to the point that Agents D and K are regarded by Clark as uncles, though moreso D than K).
  • Thor is sent to Earth to be raised in an amnesic state on Themyscira, which hides his true heritage until the time is right, to the extent that he considers Diana his sister as a child. That said, it is implied that Diana think of him as more than that.
  • Hellboy comes to Earth on the same night that Captain America 'dies', and it is later established that his father is Trigon the Terrible (with Raven, his half-sister, being raised as his daughter when she is born a few decades later).
  • The BPRD now includes Zatanna, John Constantine, Jason Blood/Etrigan, Detective Chimp, and Stanley Ipkiss/The Mask (the Mask itself being a creation of Thor's brother Loki). In later books, they are joined by Frankenstein's Monster(the DC version from Seven Soldiers of Victory) and Jack Russell, the Werewolf by Night.
  • The Nova Corps are basically a 'spin-off' of the Green Lantern Corps (Sinestro compared them to second-stringers, but considering his nature anything he says must be taken with a grain of salt).
  • The Ghost Rider is now an agent of the Spectre (who went mad at some point prior to the series, and started persecuting magic-users, which is why the Statute of Secrecy was put in place).
  • The Sentinels of Magic include Albus Dumbledore, Doctor Fate, Doctor Strange, Madame Xanadu, the Enchantress, Shazam, and Agatha Harkness.
  • Peter Parker, Jimmy Olsen, Garfield Logan, Virgil Hawkins, Johnny Storm and Victor Stone were all at high school together before most of them received their powers (or had to get their 'powers' in Vic's case) in the same accident (caused by Jack Napier , Eel O'Brian, and Flint Marko under the orders of Lex Luthor and The Kingpin, while the Fantastic Four, the Hulk, Doctor Doom, Captain Atom and Firestorm were created in another event orchestrated by Rasputin the Mad Monk.
  • Raven and Wanda Maximoff attend Hogwarts with Harry (and Constantine and Zatanna are also Hogwarts alumni).
• Infinity Crisis does this a lot, especially since the original story had expanded into a full-on MassiveMultiplayerCrossover:
  • The events of both Black Lightning (2018) and Lucifer (2016) are established to have happened on Earth-1 (the Arrowverse). Ironically, Black Lightning would end up being incorporated into the Arrowverse, but not as part of Earth-1^note until Crisis on Infinite Earths (2019), and that series also established Lucifer was set on Earth-666.
  • New Charges, set on Earth-1, has Black Lightning becoming a mentor to both Miles Morales and Static Shock.
  • In Gamma Relations, set on Earth-199999 (The Marvel Cinematic Universe), a version of the X-Men is introduced based on the X-Men Film Series.
    • Future stories would establish that the events of the Indiana Jones films, The Rocketeer, and Starman all happened on Earth-199999 as well.
  • Counterpart Conferences has He-Man and the Masters of the Universe crossed with ThunderCats.
  • Of Kryptonians and Queens reveals Lena Luthor is actually Morgan Le Fey from Merlin (2008).
  • Later, the Joker and Ra's al Ghul from the DC Animated Universe arrive on the DC Extended Universe Earth.
  • Earth-1993 is home to the Power Rangers.
  • Earth-21 is the world of Smallville
  • In Hand and Foot shows aspects of Teenage Mutant Ninja Turtles merging parts of the original comic and the 1980s cartoon series.
  • Tomorrow's Guardians shows the future of The Orville is one of several possible futures for Earth-1.
  • Counterpart Conferences also brings in Doctor Who.
  • Earth-1984 merges together G.I. Joe: A Real American Hero and The Transformers.

• It happens often in Maribat AU fics, considering the nature of the stories:
  • Some stories take advantage of the fact that one of the previous holders of the Ladybug Miraculous was Hippolyta in order to introduce Wonder Woman into the story.
  • Alfred is often made a former Peacock Miraculous holder before it was mysteriously lost, a distant relative/family friend of the Dupain-Chengs, or both.
  • There are a few fics where Marinette and Jason Todd met before Jason becomes Red Hood and Marinette becomes Ladybug which is used as another way to establish their sibling bond.
• Child of the Storm is a Mega Crossover, and the author created a completely different canon by combining all the source material canons together.
  • The magic system is a mixture, with 'Wanded' (Harry Potter) and 'Wandless' (The Dresden Files) wizards. The differences are explained by a different relationship to the same magic - Wanded magic is Boring, but Practical, easy to master, more precise, with millennia of perfected spells to learn, and practitioners are buffered from more dangerous energies by use of wands. Wandless magic is Difficult, but Awesome, being harder to master and more vulnerable to Sanity Slippage via accidental Black Magic, but granting double the lifespan, a deeper connection to magical energy, no need for wands, and a more personalised approach to magic. It's treated like being left or right handed - some people are magically ambidextrous, and the difference can be overcome with training.
  • The Marvel Cinematic Universe is followed up to The Avengers (not including movies prequels), but the events of Captain America: The First Avenger are combined with his comic book adventures and his brief cameo in X-Men: Evolution, on top of a period spent in Hogwarts mid-war when dealing with an alliance between HYDRA and Grindelwald. So in the end there's no way of telling the exact details of his life before he became "capsicle".
  • Characters from several different canons end up being related to each other (something engineered by Doctor Strange as part of The Plan to defeat Thanos), which got so complex it led to this fic being one of the only works of any kind to have their own page for Tangled Family Tree. Highlights include Harry Potter being Thor's son via an early attempt at the whole humility thing (the basis of this fic) and a cousin of Jean Grey and Maddie Pryor on his mother's side, and Clint Barton being related to Superman (by adoption) and Minerva McGonagall and Bucky Barnes (biologically). In Harry's case, at least, it gets lampshaded in chapter 52 of the sequel, by Carol Danvers: "I swear, your fucking family..."
  • The X-Men are a mixture of the Films (particularly X-Men: First Class), X-Men: Evolution, and the comics, along with a bunch of Noodle Incidents:
    • Magneto was rescued from Auschwitz by Steve and spent some time at Hogwarts as it was assumed he was a wandless wizard.
    • The original team was the team from First Class, also coordinated by Peggy Carter and with Alison, her daughter via Steve as another member.
    • Jean, Scott (here, Alex Summers' grandson), and Warren are all contemporaries, the former two being teenagers at the start of the story.
    • Wolverine joined at some point in the early 1990s, and Xavier dealt with the Weapons Plus/Weapon X program, and he acts as a teacher at the Institute along with Storm, as in Evolution.
  • Jor-El arranged his son to end up with the Kents via his connections to S.H.I.E.L.D., and at one point he fought against the Red Room alongside Peggy Carter, Howard Stark, Charles Xavier, Mar-Vell, and Teal'c and Bra'tac.
  • Wanda Maximoff is once again the daughter of Magneto, but not Quicksilver's twin, being in her mid-40s when the story starts. She was assumed stillborn by her father, after he fought Voldemort on the slopes of Mount Wundagore, and raised by her maternal relatives, before her magic and mutation came out and she was nearly executed by The White Council as a threat, with Magneto taking her to Xavier, Dumbledore, and Howard Stark for help, before Strange intervened and trained her as his successor. She would later become a member of the Order of the Phoenix, had a relationship and a child, Hermione Granger with John Constantine (naturally, an ex-Slytherin, also an Order Member), and became the godmother of Harry Potter.
  • Zatanna Zatara's parents were also members of the Order of the Phoenix, and invented a blending of Wandless and Wanded Magic before being killed, which Zatanna mastered.
  • Several intra-franchise conflicts occurred in the past, such as Alan Scott as SHIELD's counter to Magneto, Apocalypse having originally fought a collection of enemies including Black Adam and Doctor Fate, or Doctor Strange eliminating some god-like enhancements Grindelwald had acquired from a Deal with the Devil (several even) from the likes of Mephisto and Dormammu, before leaving him to Dumbledore.
  • The existence of the Spider Totems is known to the magical community and even gets mentioned in Harry's DADA class.
  • The vampires follow The Dresden Files system, replacing the Harry Potter ones, with an addition of the Grey Court to fit Marvel-verse vampires.
  • Some characters are blended together into one, such as Peter Wisdom being Regulus Black and Dudley Dursley becoming the Blob.
  • The Phoenix Force is now also Destruction from The Sandman (1989) and the source of Harry's protection via a deal with Lily Potter.
• The Friends and the High Council WMG is an attempt to do this with every Disney-owned property.
• Blood Sisters basically operates on the premise that The Twilight Saga is part of the wider mythology established in Lost Girl, with the Cullens and Quillettes part of the wider fae community, although they are considered pariahs among the fae as they make an active effort to live among humans (and in the Cullens' case, are generally looked down on due to them having started as humans rather than being born fae). It’s also noted that wolf-shifters such as Dyson are basically intended to be the same species as the Quillettes, although this required a few changes to be made to bring the two species together; the most significant change so far is that Dyson is now capable of imprinting, with Bo being his imprint.
• In Gargoyles And Turtles Unsung Defenders, when Splinter first meets the gargoyles, he observes that he heard of gargoyles from tales told by his father of how feudal gargoyles would defend their territory alongside feudal samurai.
• Of Gemstones and Watches welds the Prime Ben 10 universe and the 2016 Reboot together- multiple concepts from the 2016 show have popped up in universe, such as the original aliens, certain plot points and villains.
• Jaune Arc, Lord of Hunger establishes that the Brother Gods in RWBY are actually Celestials and Remnant is located within the Unknown Regions of the Star Wars galaxy. Additionally, both Aura and the magic on Remnant are revealed to be extensions of the Force.
• The Firefly fic “Just Folk Now” does a weld where Mal was Caleb from Buffy the Vampire Slayer, Zoe was Jasmine and Jayne was Adam, both from Angel and Inara was Adria from StargateSG1. As the title says, they’re all just normal humans now, living in the ‘verse. Fans actually weld Whedonverse canons quite often in fanfiction.
• In Digimon United, the events of Adventure, 02, and Tamers are all comfirmed to take place on the same Earth.
• Inky Future turns the future world of Splatoon into the future of Mega Man (Classic), due to the former's apocalypse happening before Mega Man X was woken up. This results in X himself awakening in a world where humans went extinct and were replaced by human-like cephalopods (aka Inklings and Octarians). It also links together Mega Man as the future of another Capcom franchise, specifically Street Fighter, due to Dr. Light having learned Ansatsuken, with his teacher implied to have been Ken Masters.
• The world of The New Age Of Monsters is an amalgamation of the entire Godzilla franchise. As a result, the backstory of many characters and events from the other franchises have been changed to fit in this new continuity
  • The Symphogears were created with Mothra's help and are powered by her song
  • The drift technology was developed by studying Saegusa Miki's brain
  • Jet Jaguar is an AI-controlled Jaeger
  • The creator of the Pacific Rim kaijus is the long-lost civilization of Mu
  • Doctor Ver and Finé are now eco-terrorists who want humanity to stop fighting and give earth back to the kaiju
  • The Evangelions are created by giving Godzilla's blood to humans
  • Several of the Evangelion angels appear as Breachers
  • The Autoscorers are Hotua that have been exiled for misusing Mothra's gift of alchemy
  • Shem-Ha is the last survivor of the martian civilization that was eradicated by King Gidorah

Films — Live-Action

• This trope has been present in horror films for a long, long time. In the Universal Horror series, Frankenstein Meets the Wolf Man triggered the tendency to pile on the monsters, insisting that Dracula, the Wolf Man and Frankenstein's Monster all existed in a common universe. This does not work well with continuity — The Wolf Man (1941) takes place in the present day while the others happen in a dimly-characterized past — but they didn't care much by that point (Universal's horror films of the '40s are strikingly dumber and more juvenile than those of the '30s).
• Predating even these examples is Fritz Lang's 1933 thriller The Testament of Dr. Mabuse. Nominally a sequel to Dr. Mabuse, the Gambler, it also incorporates Inspector Lohmann from Lang's M as the main protagonist. Blending the supervillain from a pulp thriller with the hero of a police procedural works surprisingly well, enough that a 1960s revival of the Mabuse series retains Lohmann as its protagonist.
• In all honesty, Alien and Predator were never really meant to part of the same universe. The Xenomorph head seen near the end of Predator 2 was only meant as a reference to the non-canon comic book series that was being worked on at the time. It wasn't until the Alien vs. Predator film that the connection was made completely canonical. Hints placed by Ridley Scott in Prometheus and in the latest re-edit of Blade Runner suggest that they (and of course the rest of the Alien franchise, and transitively Predator) share the same continuity.
• Toho's giant monster movies Godzilla (1954), Rodan (1956) and Mothra (1961) were originally standalone films about unrelated monsters, but they all gradually became part of the loosely defined Godzilla universe over time. The crossover film Mothra vs. Godzilla was the first step, but the mega-crossover Ghidorah, the Three-Headed Monster took it a step further when Godzilla and Mothra teamed up with Rodan against King Ghidorah, and Destroy All Monsters took it up a notch when it threw in Manda (from Atragon), Baragon (from Frankenstein Conquers the World), Varan (from Varan, the Unbelievable), and Gorosaurus (from King Kong Escapes), as well as the addition of Maser Cannons (from War of the Gargantuas). Later on, Godzilla Vs Spacegodzilla introduced Moguera (from The Mysterians) into The 'Verse, with ancillary material establishing that the Moguera from the former film was inspired in-universe by the original; while Godzilla: Tokyo S.O.S. gives Kamoebas (from Space Amoeba) a posthumous cameo. Two Continuity Reboots later, the series' Grand Finale Godzilla: Final Wars even added the Godzilla from the 1998 American remake (now renamed "Zilla")... who promptly got his butt kicked by the original Japanese Godzilla.^note  Similarly, the Alternate Continuity film Godzilla, Mothra, King Ghidorah: Giant Monsters All-Out Attack! acknowledges the existence of the American Godzilla, but establishes that he was a different monster who was mistaken by the americans. The english dub of said film also references Godzilla: The Series. The animated film, Godzilla: Planet of the Monsters, also slots Dagahra (from Rebirth of Mothra 2) and Dogora (from Dogora) into the mix.
  • Subverted with King Kong vs. Godzilla and its sequel King Kong Escapes. The films ostensibly take place in the same universe as King Kong (1933), but they take a Broad Strokes approach to it, and Toho's Kong is quite different from the American one. He lives on "Mondo Island" instead of "Skull Island", he's considerably bigger (thanks to some powerful magic berries), and he has a much more human-like face. Oh... and he can shoot lightning out of his hands.
• Full Moon Features has done this a lot over their existence, complete with direct Crossovers like Dollman vs. Demonic Toys, characters cameoing in other movies, and The Gingerdead Man being a regular recurring character in the Evil Bong series now that his series is done. Ironically, there's also Puppet Master vs. Demonic Toys, which was originally a Full Moon production but was licensed out and made by Syfy, which Full Moon's founder Charles Band now counts as non-canon to both the studio and the series.
• Besides all the above, other crossover horror films such as Freddy vs. Jason, Sadako vs. Kayako and Lake Placid vs. Anaconda are all further examples.
• Quentin Tarantino has created a largely common universe of his films by including subtle crossreferences (for instance, characters commonly refer to others; Mr. White mentions Alabama and Mr. Blonde has Scagnetti as a parole officer, Vic Vega and Vincent Vega are brothers, etc.) and cameos, but he says that his movies are divided into two universes.
  • The first is an alternate reality where Hitler was shot down in a theater causing Americans to be obsessed with pop culture and extremely violent, which consists of Pulp Fiction, Reservoir Dogs, True Romance, Inglourious Basterds, Death Proof and possibly Django Unchained.
  • The second is a universe that takes place in Tarantino movies that are supposedly released in both the real world and the main Quentin Tarantino Universe, which consists of Kill Bill, From Dusk Till Dawn, Natural Born Killers, and possibly Machete and Planet Terror because of cameos of Earl and Edgar Mcgraw in both movies. Interestingly, the title character in Machete appears in another of Robert Rodriguez's films: Spy Kids.
  • Tarantino has also stated that Django and his wife Broomhilda are intended to be the ancestors of John Shaft.
• An interesting example occurs with the Cloverfield franchise, which ended up having to be welded to itself. The first film was a standalone found-footage movie, and despite numerous Sequel Hooks, nothing came of them for a very long time. The next time the series' name showed up was 10 Cloverfield Lane, a film which had practically nothing to do with the original and felt very much In Name Only; rather than a found footage film, 10 Cloverfield Lane was a psychological horror film, and dealt with a human villain and an alien invasion rather than a giant monster attack. Wild Mass Guessing abounded on how these two films actually connected. It wasn't until the third film, The Cloverfield Paradox, that the true relationship between entries becomes clear; said film also serves as a prequel to the original Cloverfield, and sees Clover itself (or another member of the same species) appear at the very ending.
• The 1980s/'90s series of Superman and Batman films made no reference to each other and given their vast differences in tone might have been assumed to take place in very different universes (despite their comic books having long been from the same universe), until Bruce mentions that the circus Dick had performed with "must be halfway to Metropolis by now" in Batman Forever. That didn't prove it for everyone, though (Metropolis might just be another city in Batman's world, die-hards argued); it wasn't until the next movie that the canon welding was made official, in the most cringe-inducing way possible.
  Robin: [checking out the Batmobile] I want a car. Chicks dig the car!
  Batman: [turning to camera] This is why Superman works alone.
• An unusual example comes from SHAZAM! (2019), set in the DC Extended Universe — a social worker who appears previously appeared in another film from the same director, Lights Out (2016), which was a horror film with no connection to DC Comics.
• Once New Line Cinema took over the Friday the 13th franchise from Paramount, the first film they made, Jason Goes to Hell: The Final Friday, ended with a crossover hook indicating that it was set in the same universe as A Nightmare on Elm Street, New Line's marque Slasher Movie franchise. Horror fans had long dreamed of a showdown between the slasher icons Jason Voorhees and Freddy Krueger, but Paramount and New Line could never agree on a script. Nine years of Development Hell later, New Line followed through with Freddy vs. Jason.
• Jay and Silent Bob Reboot retroactively brought Zack and Miri Make a Porno into The View Askewniverse by having Brandon make a cameo early on as a Hollywood lawyer. The film couldn't explicitly name him, however, as Kevin Smith didn't own the rights to Zack and Miri.
• An averted example was supposed to happen with Mathilda, which would have been not just a sequel to The Professional but it would have also contained references to Luc Besson's previous assassin film La Femme Nikita thus placing all three films in the same universe per Word of God. However, because Besson was estranged from Gaumont and unable to get Natalie Portman interested in the project, he decided to make it a standalone movie titled Colombiana with Zoe Saldaña in the lead role.
• Another aversion happened with Maniac Cop 2. Director William Lustig originally wanted to cast Joe Spinell, who played the Serial Killer Frank Zito in Lustig's previous slasher Maniac! (1980) (which he also wrote the screenplay for), as the villain and have both that film and the Maniac Cop series take place in the same universe, but Spinell died in a bathtub accident before production began. This film's serial killer co-villain was subsequently rewritten into a Suspiciously Similar Substitute.
• Spider-Man: No Way Home: The movie involves characters from alternate universes being pulled into the Marvel Cinematic Universe — specifically, villains from the Sam Raimi Spider-Man trilogy and the Amazing Spider-Man movies, making those two movie universes part of the greater MCU-established multiverse. The post-credit scene of this movie and Venom: Let There Be Carnage also makes that incarnation of Venom and Sony's Spider-Man Universe part of the larger MCU Multiverse.
• Spider-Man 2: A stunt double of Thomas Jane made a Cameo at the end of the movie. According to the DVD Commentary, this is supposed to be Frank Castle.
• An interview about Danger Diva confirmed the film is set in the same universe as Shredder Orpheus, with both films being set in Seattle, having the Grey Zone as a place for the poor, shared technology like hypno-pulses, Shredder actors being cast in similar roles, and sharing high-concept mythological themes.
• Guillermo del Toro has confirmed that two gureilla fighters killed in Pan's Labyrinth are Carlos and Jaime from his earlier film, The Devil's Backbone.
• Several Disney live-action films of the 1960s and 70s share a loosely-connected universe. The main antagonist of The Absent-Minded Professor and sequel Son of Flubber, Alonzo Hawk (Keenan Wynn), later appeared the Big Bad in Herbie Rides Again (he also played an Expy in two other films, Snowball Express and The Shaggy D.A.); the bumbling cops from The Shaggy Dog, Hanson and Kelly, also appear in TAMP. The setting of TAMP and SOF, the fictional Medfield College, was also the setting for a trilogy of later films featuring Kurt Russell as Dexter Riley: The Computer Wore Tennis Shoes, Now You See Him, Now You Don't, and The Strongest Man in the World.

Gamebooks

• The ninth Fighting Fantasy gamebook, Caverns of the Snow Witch, took the player on a tour of the major locations from two of the previous books (The Warlock of Firetop Mountain and The Forest of Doom), establishing that they all took place in the same land of Allansia. (It also name-checked a character from Forest of Doom.) The monster manual Out Of The Pit then expanded this world: Allansia and The Old World, the setting for the Sorcery! series of gamebooks, were two continents on the world of Titan.

Live-Action TV

• All of Chespirito's works have long been implied to be set in the same universe. Indeed, El Chavo (del Ocho) and El Chapulín Colorado had met at least once.
• Steven Moffat has welded a fair number of his series together over the years: Chalk contained frequent references to Press Gang, and was in turn referred back to by Coupling; Jekyll also referred to Press Gang and Coupling has references too.
• Arrowverse:
  • After John Constantine's show on NBC was cancelled, a deal was struck to bring the character into Arrow (and by extension, the Arrowverse) for a guest spot, played by the same actor using the same props and costumes, and thus importing that show into the larger franchise.
    • Later, Constantine performs the very rare reverse Spin-Off, and becomes part of the Legends of Tomorrow ensemble.
  • The Flash (2014) has the multiverse as a large part of the arc of its second season. In the episode "Welcome to Earth Two", two of the alternate worlds shown as The Flash (1990) and Supergirl (2015). Since then, Supergirl has become one of the core shows of the 'verse, while the 90's Flash has made a couple of appearances.
  • The 'verse's Crisis on Infinite Earths (2019) crossover caused a boatload of this:
    • Black Lightning (2018) started off as the only superhero show on the CW not part of the Arrowverse... until it was announced that Black Lightning would be appearing in the crossover, although the show itself would not be devoting an episode to it.
    • Brandon Routh also appears reprising his Superman, the one from Superman Returns, who is also supposed to be the one from Superman: The Movie.
    • Tom Welling and Erica Durance reprise their roles as Smallville's version of Superman and Lois Lane in a cameo appearance, Robert Wuhl cameos as Alexander Knox from Batman (1989), we get a glimpse of the Dick Grayson from the original Batman TV show, Lucifer Morningstar from his titular series briefly encounters some heroes, and Ashley Scott appears as Helena Kyle from Birds of Prey (2002). Meanwhile, stock footage of Titans (2018), Stargirl (2020), Doom Patrol (2019), and Swamp Thing (2019) appear at various points in the show.
    • Last but not least, Ezra Miller reprises their role as the cinematic Barry Allen from the DC Extended Universe.
• Russell T Davies has suggested that Adam Mitchell's mum in Doctor Who, played by Judy Holt, may be the same person as Sister Mitchell in Childrens Ward, also played by Judy Holt, which would bring RTD's earlier programme into the Whoniverse. He was probably joking. He also slipped a reference to "the Vivaldi inheritance in 2004" into Torchwood: Miracle Day, referring to his ITV series Mine All Mine ... which included Gareth David-Lloyd as a character called Yanto Jones, only one letter off from his Ianto Jones in prior series of Torchwood.
• Thanks to its importation of the Homicide: Life on the Street character John Munch and its numerous other crossovers (some involving him, others not), the Law & Order franchise managed to bring in NCIS, NCIS: Los Angeles, JAG, First Monday, In Plain Sight, The Beat, Hawaii Five-0, The Wire, Arrested Development, The X-Files, The Lone Gunmen, and Millennium (1996) all into a single universe. Also, Sesame Street, if you count Muppet versions of the character. All this also fits into the Westphall Hypothesis above.
  • The scariest part of that link? The X-Files crossed over with COPS, a reality show, meaning that all those shows take place in our universe.
  • NBC has also announced a crossover between Chicago P.D. and Law & Order: SVU, this means that Chicago P.D. and Chicago Fire are also part of this verse.
• Later Kamen Rider shows have taken steps to establish that the various characters created by Shotaro Ishinomori (or at least Alternate Universe versions of them) exist in the same universe. For example, characters from Space Ironmen Kyodain appeared as the antagonists of one of the Kamen Rider Fourze movies, while Inazuman appeared in the crossover movie between Fourze and Kamen Rider Wizard. Kamen Rider Gaim also had a crossover with Kikaider designed to promote the latter's new movie.
• The Disney Channel has done several crossovers with their live action series, so that psychics, wizards, Tipton Industries, President Martinez, Iron Weasel, and Hannah Montana all exist in the same universe.
• It's been more-or-less established that all Nickelodeon sitcoms beginning with Drake & Josh all have some form of connection. Eventually enough crossovers happened for the Nick Verse to form. It is horrendously complicated by the fact that due to the way it came about, the actors and characters all exist alongside each other as real people. It includes Drake & Josh, Zoey 101, iCarly, Victorious and also causes Big Time Rush and The Naked Brothers Band to enter the universe, via Miranda Cosgrove showing up As Herself on both those shows. This could somewhat more accurately (and awkwardly) be referred to as the Schneider-verse, for showrunner Dan Schneider.
• Lisa Kudrow, who played a quirky waitress on Mad About You, played Phoebe on Friends. It was later revealed they were twin sisters and Ursula (the waitress) became a recurring character. It was also revealed that Paul once lived in the apartment now occupied by Kramer on Seinfeld.
  • In the second season of Friends, there was a brief crossover with Caroline in the City. Matthew Perry had a brief appearance on the Caroline episode as Chandler while Lea Thompson had an appearance Caroline in the Friends episode. Expanding beyond those two, earlier that same season Niles Crane and Daphne Moon appeared in one Caroline episode, and Frasier himself showed up in an episode of Wings. Based on this logic, potentially every NBC sitcom that ran during the 90's takes place in the same world (and also proceeds to directly tie into the Westphall example below).
• There was a crossover between Murder, She Wrote and Magnum, P.I., and one between Magnum, P.I. and Simon & Simon. Accordingly, all three are in the same universe.
  • An obscure '50s Film Noir called Strange Bargain is also in the same universe as Murder She Wrote. The episode "Days Dwindle Down" is actually a sequel to Strange Bargain, featuring many of the original cast members reprising their roles, and Jessica uncovering the identity of the real killer from the movie.
• Marcia Wallace appears in what at first appears to be a Casting Gag as one of Murphy Brown's many, many secretaries. Then, at the end of the episode, Bob and Jerry show up, begging her to come back to Chicago. Ergo, Murphy Brown takes place in the Bob Newhart 'verse. What effect the series finale of that show has on Murphy & Co. is a Riddle for the Ages.
• Although the Showtime revival The Outer Limits (1995) was an anthology show, it usually ended its seasons with money-saving clip shows tying multiple prior episodes together into a single continuity.
• Power Rangers has gone through this a few times. While the first six seasons were all one storyline and the seventh (Power Rangers Lost Galaxy) was a direct sequel, each one past that has been self-contained; though many would make small references to prior seasons or at least eventually team up with the prior season's cast. Only two seasons (Power Rangers Ninja Storm and Power Rangers RPM) have been welded in after the fact, having nothing in themselves to connect to the rest of the franchise; and the third unconnected season (Power Rangers Jungle Fury) has been welded into Power Rangers Megaforce's Crisis Crossover. Also notable was that Power Rangers Lightspeed Rescue welding itself to Lost Galaxy retconned the latter from 20 Minutes into the Future to the present day. (Lost Galaxy also once referenced the universal coordinates of the Doctor's homeworld Gallifrey.)
• Rumors abound to this day that Patrick McGoohan's Number 6 from The Prisoner (1967) is the same character as John Drake, his role in the earlier series Danger Man. McGoohan always denied it while other people involved in the show supported it, in what was probably a deliberate attempt to screw with the fans some more.
  • It's been suggested that McGoohan tended to deny it solely because he didn't hold the rights to his previous role, and thus, establishing a direct connection could be considered copyright infringement and therefore actionable. His co-writer on the series has always claimed that it was definitely Drake.
• The 1970s ITV relaunch of The BBC sitcom The Rag Trade had Peter Jones and Mirian Karlin reprising their roles from the sixties series, confirming they were in the same continuity ... and also added Olive from the same creators' On the Buses. (The character of Reg Turner played by Reg Varney wasn't in the relaunch, so Olive didn't wonder why he looked like her brother Stan.)
• In the last episode of Spin City where Michael J. Fox appears as a regular, it is suggested that the series takes place in the same universe as Family Ties.
• Taking this to the extreme, due to various character cameos and crossovers, much of television history may take place in the mind of St. Elsewhere's Tommy Westphall.
• The Super Sentai franchise used to be separate from each other. This changed with Kaizoku Sentai Gokaiger, putting them all together in one big universe. This was further expanded in the movie Kaizoku Sentai Gokaiger vs. Space Sheriff Gavan: The Movie, which brought over the Metal Heroes franchise, which was further expanded when Gavan's successor, Gavan Type-G, appeared in Tokumei Sentai Go Busters and Sekai Ninja Sen Jiraya in Shuriken Sentai Ninninger.
• The Ultra Series: Originally, the first three shows had minimal connections aside a few minor nods here and there. However, with Return of Ultraman, they were united into a singular continuity that followed for the rest of the Showa era, as well as with the Heisei series Ultraman Mebius and Ultra Galaxy Mega Monster Battle (which ends up creating a lot of contradictions as a result). Then, with the Ultraman Zero movies, the remainder of the franchise was linked up with the Showa universe to create a massive multiverse, and then afterwards it gets super-confusing from there.
• In Gran Hotel, Detective Ayala, played by Pep Antón Muñoz, investigates crime around a big fancy hotel during the first decade of the twentieth century. In Alta Mar (set in the 1940s), Doctor Ayala, also played by Muñoz, boards the Barbara de Braganza and tells the head of ship's security that his father was a criminal investigator. Confirmed by Word of God that the characters are meant to be father and son.

Myths & Religion

• Robin Hood went through several rounds of this, along with Adaptation Displacement. Maid Marion (or "Marian"), Friar Tuck, and Alan-a-Dale were all characters from separate folk tales, and it was only later that Robin Hood stories had anything to do with Richard the Lionheart or Prince John.
• The Equivicatio Romana by which each of the gods and goddesses of the other pantheons the Romans encountered was said to be another name for the nearest equivalent in their pantheon—sometimes by a great deal of squinting.
• Euhemerism which postulates that the pagan gods and goddesses were actually great heroes and heroines who lived long ago and whose reputations snowballed until they became gods.
  • Herodotus one-ups Euhemeris by trying to equate Egyptian mythology and Greek mythology.
• The two Classical Mythology stories that bring together large numbers of Greek heroes likely have their origins in Canon Welding: the Voyage of the Argo and the Calydonian Boar Hunt both feature characters like Herakles, Theseus, Bellerophon and so on.
• Historia Regum Britanniae weaves The Aeneid, The Iliad and The Odyssey into Arthurian Legend by having Brutus of Troy sail to pre-Roman Britain and found a new empire with New Troy (aka London) as the capital which sets the stage for Arthur and the Knights of the Round Table.
• A lot of theological ink has been spilt over two millenia in attempting to draw out a coherent welding of the often contradictory themes of the Old and New Testaments of The Bible, with insertions and foreshadowing of the mission of Jesus Christ drawn (often very tenuously) from the older religious texts. The Old Testament is effectively being retconned to include Jesus and to give the whole a greater coherence. All this began with the earliest Christian writers like Paul of Tarsus, who asserted Jesus had been predicted by Old Testament prophecies, in interpretations the Jews rejected. The main problem with linking the Testaments comes from later Jews not wanting anything to do with Jesus, and Gentile Christians not wanting Jesus "tainted" by Judaism, and both groups misunderstanding one another. Given how many times the New Testament references the Old Testament, the thematic links between the two (a promised land, a chosen people, God's blessing and kingship, etc.), and the professed Judaism of many of the authors, it's clear the New Testament authors meant the two testaments to be read together.

Pinballs

• The Party Zone takes three of Dennis Nordman's games — Party Animal, Elvira and the Party Monsters , and Dr. Dude — and gives them in a shared continuity they never had before.

Podcasts

• The hosts of Mom Can't Cook! often indulge in this between different films that, ostensibly, have nothing to do with each other. Most notably, they declare "reindeer flu" from 'Twas the Night and "the Spanish rice problem" from Hounded to be one and the same, and then when Spanish rice is brought up in Stuck in the Suburbs as being "too spicy" for Brittany's dad, they declare he's inadvertently saved her from this disease. References to Agent Simms from First Kid keep appearing in subsequent episodes as well.
• Pokémon World Tour: United establishes in its first episode that the series takes place twenty years after the events of the Pokémon Red and Blue video games, with Red being a Pallet Town hero and Blue being the first Gym Leader Rose and Cobalt face. However, the end of act one reveals that the new regime of Team Rocket is led by characters from Pokémon: The Series specifically Jesse and James. Further, other characters from the anime, Butch and Cassidy, are aligned with a separate faction of Team Rocket that's A Lighter Shade of Black. Later, when exploring the old Rocket hideout in the Celadon City Game Center, Cobalt uncovers a document describing the new regime's rise in power, which includes mentions of Ash and his frequent battles with grunts Jesse and James and their talking Meowth. This all amounts to show that, in this version of the Pokémon universe, the events of the game and the events of the anime both occurred.

Radio

• The Green Hornet was the son of The Lone Ranger's nephew back when the two were on the radio. However due to legal issues between those who currently own the two franchises, the connection isn't used at all anymore.
• When The Last Chance Detectives were adapted to radio, their premiere episode included an appearance by Jason Whittaker of Adventures in Odyssey, welding the two previously unrelated Focus on the Family franchises.

Roleplay

• Any Journal Roleplay, MUSH, or similar roleplay which allows characters from multiple works of fiction must in some way explain how the crossover occurs. While the Inn Between the Worlds or the "spooky jamjar," in which the various characters somehow travel or are transported from their home settings into an original setting, is probably most common, some roleplays opt instead to adapt the source works into a single shared world. This is especially common for roleplays themed around a specific genre or franchise: notable examples include Mega Man MUSH, Persona MUSH, Super Robot Taisen MUSH and its Spiritual Successor Super Robot Wars MUSH, Videoland MUSH, and many others.
• Mahou MUSH is a Magical Girl-themed game set in Tokyo, the setting of which adapts many magical girl series (and a number of original player-created themes) into a single continuity. Prominent themes thus adapted include Magical Girl Lyrical Nanoha, Puella Magi Madoka Magica, various Pretty Cures (particularly HappinessCharge Pretty Cure!), Sailor Moon, and Shugo Chara!.

Tabletop Games

• BattleTech: Michael A. Stackpole has revealed in a 2002 German interview that Wolf's Dragoons unintentionally became an advance recon force for the Clans while the writers were planning out the Clan Invasion. Specifically, during a convention in 1988, Stackpole and Battletech co-creator Jordan Weisman were speculating about Natasha Kerensky's connection with Alexandr Kerensky when Stackpole noted the coincidence of Wolf's Dragoons and one of their planned Clans sharing a name. Since the Dragoons already had a mysterious past, the writers were able to cleanly connect them to the Clans.
• Delta Green has a complicated one between Robert W. Chambers' "The Maker of Moons", Colin Wilson's "The Return of the Lloigor", The Cruel Empire of Tsan-Chan (a monograph for Call Of Cthulhu roleplaying game which expands on Lovecraft's The Shadow Out of Time) and Lovecraft's short story The Call of Cthulhu. The Kuen-Yuin, a cabal of Chinese sorcerers from "The Maker of Moons", are described as descendants of the Priest-Kings of Mu servants of the Lloigor (which are equated with the Xin from "The Maker of Moons"), the “deathless ones in the mountains of China” that control the worldwide cult of Cthulhu in "The Call of Cthulhu", and the small cadre of immortal sorcerers who rule over the Cruel Empire of Tsan-Chan (mentioned in a line of "The Shadow Out Of Time"), which will arise 5000 years in the future, after Cthulhu woke and humans went insane ("Dreamers"), finally casting good and evil aside and becoming like the Great Old Ones: shouting and reveling in a holocaust of ecstasy. Some material even suggest this future is incompatible and competing with the Yithian's plan to wipe out mankind as seen in "The Shadow Out Of Time".
• An odd version of this exists in Dungeons & Dragons. Gods cross over from one campaign setting to another, spells exist under different names, and so on. Initially the settings were welded only by implication, mostly mythological crossovers (shared gods) and in the names of spells (Bigby's grasping hand, Mordenkainen's hound) indicating that divine beings and powerful wizards COULD travel between them, but providing no actual explanation. Later, the Planescape and Spelljammer meta-settings provided two (amusingly contradictory) explanations: in Planescape a stock-fantasy multiverse exists, with the added benefit of explaining where all the more biologically impossible elemental and evolutionarily improbable critters come from. Spelljammer is based on medieval cosmology, and adventurers can sail between the various crystal spheres in mighty magical craft riding currents in the luminiferous aether.
  • There was also the World Serpent Inn, which even links campaign settings which are explicitly not part of the Planescape/Spelljammer cosmology, such as Eberron.
  • Ravenloft is, itself, a product of Canon Welding, as its Patchwork Map incorporates several domains that were inspired, copied, and/or outright stolen from other AD&D campaign worlds. Literally stolen, in some cases.
  • The "legendary" settings of the various AD&D Historical Reference books were eventually revealed in the Chronomancer appendix to be the past of Gothic Earth from Ravenloft's Masque of the Red Death ...which in turn may be the past of one of the magical d20 Modern settings — probably Shadow Chasers (the Red Death gets mentioned in the Menace Manual).
  • In D&D 4th Edition, there was a policy to enforce uniformity across the gameline by inserting setting elements from the core material into all official D&D settings, and retcons and setting-shaping disasters were applied wherever necessary to make it so. For example, the cosmology of the Forgotten Realms had to allow for such things as the Primordials and the Feywild because those were part of the Nentir Vale cosmology. However Dark Sun in 4e was largely able to maintain its independence from such core elements, either by slapping new names on old Athasian material (and often ignoring them afterwards) or by rejecting them entirely if they couldn't. (This is in part helped by Dark Sun's traditional independence from the rest of the D&D line; crossovers were firmly discouraged even at the height of the TSR and Planescape days.)
  • The D&D 5th edition supplements Plane Shift: Innistrad and Plane Shift: Zendikar enable campaigns to be set in the Magic: The Gathering multiverse.
• The Old World of Darkness started off as a set of tabletop RPGs each designed as a stand-alone, but since they shared the same basic gameplay and theme, crossovers were an obvious possibility. White Wolf acknowledged this by grouping them together, but they don't all fit that well. Vampire: The Masquerade has a Biblical origin story, while Werewolf: The Apocalypse has a pagan backstory. Vampires and mages are both supposed to have secret societies manipulating human history for centuries at least, with directly conflicting goals, yet there's only one case in canon of them fighting each other. And several games have a metaplot pointing to the forthcoming end of the world, but all have a different scenario for it. When it came to mechanics, mages can curbstomp any of the other supernatural beings unless caught unaware (especially vampires, since the best way to counter mages' magic is to be alive).
  • From the very first edition of Vampire, it was implied that the Tremere vampire clan were connected to House Tremere in the earlier Ars Magica game (which shared some design staff with Vampire). This was later dropped, as the rights to Ars Magica shifted publishers, and the later Vampire: The Dark Ages setting explicitly took place in the same time period as Ars Magica, but told a very different version of the story.
  • The New World of Darkness is made with the possibility of such crossovers explicitly in mind, at the same time keeping each group generally out of each others' way. For example, the Supernal Realms of Mage: The Awakening and the Shadow World of Werewolf: The Forsaken have little to do with each other, but equally don't step on each other's cosmological toes.
  • Exalted was an inversion. The original concept for the game was for it to be set in the forgotten, mythical prehistory of the Old World of Darkness... but it was ultimately decided not to make this an absolute of the setting, and reduce the connections to common setting elements and parallels that hint at the possibility. The tagline "Before there was a world of darkness..." is The Artifact of the original concept.
• Rifts:
  • Want Robotech mecha to fight the Teenage Mutant Ninja Turtles alongside unicorn-riding cyborgs, only to have them all ambushed by eldritch abominations? Have at it! Palladium Books specifically published conversion books for incorporating their other franchises into Rifts rules.
  • The Rifts Chaos Earth RPG (which takes place during The Great Cataclysm) explicitly state that Rifts is the future of the Beyond the Supernatural setting. This had previously been Kevin Siembieda's headcanon, but he hadn't wanted to firmly state it because Rifts was also supposed to be our Earth's future.
• The Warhammer and Warhammer 40,000 universes used to be linked, although the linking statements were made by mad characters. The whole saga/background is told through an Unreliable Narrator anyway. Games Workshop has stated that the link is now done away with, since it was mostly silly anyway. The world of Warhammer used to be a planet in the 40k universe, surrounded by warp storms that made it inaccessible for the rest of the galaxy. Nowadays, they exist in separate universes, but there appears to be a small link between them in the form of the Warp (the Chaos Gods are the same in each universe, and some people in Warhammer's world have gotten visions of Chaos in the Warhammer 40,000 universe. For example, in Liber Chaotica: Book of Khorne, it's all but outright stated the author is having visions of Abaddon's 13th Black Crusade. Also the Old Ones in Warhammer appear to be the same as the ones in 40k, and a fan theory suggests they escaped from the 40k universe to the Warhammer one after the War in Heaven, or that the opposite happened and they were forced to abandon it to fight in the War in Heaven). There is no real interaction between the two universes, however, unless you count some daemon characters popping up in both universes and a few magic items that have a suspicious resemblance to 40k technology. It also used to be fairly heavily implied that Sigmar (the fantasy Empire's messiah figure and founder) was one of the missing Primarchs (genetically enhanced superhuman offspring of 40k's Emperor). Warhammer 40,000 was later considered to be simply the Spiritual Successor where everything is an expy of the original Warhammer Fantasy. Nowadays they are implied to share the warp and it's left at that, with the Sigmar is a lost Primarch angle explicitly dropped and as aforementioned the Old Ones are implied to be the same in both universes.
• The GURPS Infinite Worlds setting ties together every alternate universe they ever came up with and every licensed work ever adapted to GURPS from Uplift to Discworld to Hellboy.

Theme Parks

• In Jimmy Neutron's Nicktoon Blast at Universal Studios, all of the Nicktoons are shown as existing together in a large multiverse, with the soundstages acting as portals between their worlds.
• In Disneyland Paris, the story of the town of Thunder Mesa (the park's version of Frontierland) ties together Big Thunder Mountain and Phantom Manor in a tragic tale of a haunted bride
• The Society of Explorers and Adventurers storyline at the Disney Parks grew from a backstory for Tokyo Disney Sea's Fortress Explorations into a shared universe incorporating that same park's Tower of Terror, Hong Kong Disneyland's Mystic Manor, the extinct Pleasure Island and its Adventurers Club, the unbuilt Discovery Bay and its affiliated films, the Jungle Cruise and the Indiana Jones films (which themselves were previously connected to the Jungle Cruise by backstory for the Indiana Jones Adventure).

Toys

• Transformers:
  • Pepsi Convoy is made of sentient metal, the substance that makes up Pepsiman.
  • The "Alternity" toy line links the alternate universes of Binaltech, Binaltech Asterisk, and the Kiss Players radio drama, based on the Japanese Transformers: Generation 1, and Micron Densetsu, the Japanese version of Transformers: Armada, and the Action Figure File Cards of the Transformers Film Series toy line, and the game Transformers: Convoy no Nazo.
  • G.I. Joe is referenced with the Transformers: Energon Snow Cat (Cyclonus) transforming into a Snow Cat vehicle, the Transformers Timelines subscription exclusive "Serpent O.R." referencing Serpentor, and the Transformers: Generations Combiner Wars Viper turning into a Cobra Rattler plane with a combined Cobra/Decepticon insignia. Exclusive sets from San Diego Comic-Con and the Transformers Collectors' Club combine both series.
• Through commercials, The Trash Pack, Shopkins, and The Grossery Gang, all blind-bagged rubber figurines by Moose Toys, share a world.

Web Animation

• Everything Is Broken: Parts 1 – 3 were originally titled Luna Game In A Nutshell and parts 4 – 6 Amnesia In A Nutshell. They were their own separated series until their titles were changed to HTF + Luna Game and HTF + Amnesia, with the two being formally connected in HTF + Amnesia (Part 3)/HTF + Luna Game (Part 4).

Webcomics

• The MS Paint Adventures series Problem Sleuth ties into the two comics that predate it:
  • Jailbreak ties into it when Zombie Ace Dick and his whale crashed into the jail where Jailbreak was set. Indeed, a dead whale was part of an early Jailbreak puzzle, and ZAD and the Completely Sane Man were revealed to be the skeletons in one of the cells. Another Ace Dick comes across the forest where two of the jail's prisoners escaped to, as well as the tree stump where they died.
  • The events of Bard Quest appear to end at around the same time Ace Dick plays his Game of Life session, as the swamp he trudges through during the Oregon Trail segment is shown to be Bard Quest's Swamp of Mystery. The Bard's party is stuck in the same poses as one of its last panels.
• Homestuck's Comic Within A Comic Sweet Bro and Hella Jeff predates Homestuck. It was originally written as a parody of another Webcomic called Higher Technology, and was written into Homestuck as a Webcomic run by Dave Strider.
  • In a semi-canonical donation extra the Problem Sleuth characters did battle with the Midnight Crew. That gang would later become extremely plot important in Homestuck. Even though both Problem Sleuth and the Midnight Crew exist as fictional works in the Homestuck universe — in fact, instead of Homestuck, in-universe the adventure following Problem Sleuth was based on The Midnight Crew. To confuse the issue further, an Easter Egg in Homestuck implies that Problem Sleuth starred a group of the natives of Prospit, making Problem Sleuth (and technically the rest of MS Paint Adventures, as seen in its own section) canonical to the Homestuck multiverse, though where it fits was never hinted at.
    • In Homestuck^2, Problem Sleuth actually ends up being involved with the events of the story, helping Dad Crocker and Diamonds Droog while the former is in Midnight City.
• In Starslip Crisis, the character of Vore is all but explicitly stated to be in fact Vaporware from the author's previous comic, Checkerboard Nightmare. However, this can be considered only to be a partial example, since said strip's events are never mentioned in Starslip and Vore himself seems to have lost his memory up to that point, causing a bit of a personality change (yes, Vaporware also expressed desires to exterminate mankind, but Vore's a lot more proactive about it), so for all intents and purposes Vore can be considered a separate character. Eventually he did regain his old memories and personality, and started calling himself Vaporware again...right before he was killed off for real. But records of the past (or Real Life, 21st Century Earth) seem to be extremely sketchy, as evidenced by the Show Within a Show "Concrete Universe," where covered wagons exist at the same time as cloning.
• Crossover Wars and The Crossoverlord established many webcomics as part of the same multiverse with rules more akin to Westphall's mind. The Realitease page done by Crossoverlord creators contains interesting informations about which webcomics happens in the same universe with lists of proofs and explanations:
  • Fans! and College Roomies from Hell!!! seems to be set not only in the same universe but also share it with eight other webcomics.
  • Something*Positive shares a world with Queen of Wands, Punch an' Pie, Scandal Sheet, Girls with Slingshots, Questionable Content, Shortpacked!, Penny and Aggie and All New Issues. For example, the cats from S*P and GWS had a litter of hypoallergenic kittens.
  • MegaTokyo, Applegeeks, Ctrl+Alt+Del, Questionable Content, Shortpacked! and Diesel Sweeties are all set in one universe. Also, one of the hypoallergenic kittens of Choo-Choo Bear and Sprinkles ("the fat one") was given to Leslie Bean by her lesbian lover's sister, Roz in a weird, drug deal-like handoff with Davan. In the words of David Willis, "Webcomics are so incestuous".
  • Mindmistress shares a universe with Clan of the Cats and LCD, as well as with Zebra Girl or her alternate counterpart.
  • Crossoverkill fueled the fire, not only adding more webcomics to The Multiverse, but also with revelation that Doppleganger Gang members are all alternate reality counterparts of one another and there are members from viarous webcomics among them, including several fantasy webcomics.
• Heroes Unite did it with a horrifying amount of Super Hero webcomics, hosted on Drunk Duck. First it established that Energize, Bombshell, and an alternate counterpart of Acrobat share an universe, and then a bunch of other superheroes joined in. Some writers even took an advantage of it to make their webcomics more popular. The creators of Energize and Dasien did a short (currently on hiatus) crossover between their characters, while the former used a new Shared Universe to bring back his other webcomics - Fearless, SHELL teamed up with The Blonde Marvel and Bombshell and gets his ass kicked by one of Hero Force members before joining HU, and Vora, Princess Of The Skies, appeared a few times in HU before getting her own adventures. And it's all one reality in The Multiverse of the webcomics. Having kickstarted the whole superhero crossover thing on Drunk Duck, Heroes Unite is now set in its own self-contained universe, but the crossover goodness continues in the spinoff Heroes Alliance with the characters from Karabear Comics Unlimited and even involved Jenny Everywhere and golden age characters like Madame Fatal.
• T Campbell has done this with various webcomics he's written or co-authored, both played straight and using alternate versions of characters.
  • Penny and Aggie, Cool Cat Studio and Sketchies are set in the same universe. However, the SF and supernatural elements in Cool Cat Studio are absent from the other two comics. Campbell once explained this on the P&A forum by stating that such elements exist on the periphery of the comics' shared universe, so not all its inhabitants experience, nor are even aware of, such things.
  • This is in contrast to the Fans! universe (and its alternate versions of P&A's characters), where, particularly after the Revival, paranormal occurrences are so frequent and prominent that the entire world is aware of them. Also, alternate versions of characters from Penny and Aggie and Fans! appear in each other's universes every so often.
• Barry T. Smith's Ink Tank appeared to be in an entirely new universe from the previous strips...until a story arc which ended with the Author Avatar having a nervous breakdown was resolved by Dante from Angst Technology turning up and treating him to a coffee.
• Artist Ursula Vernon's Digger, an anthro adventure about a mildly cynical wombat and a statue of the god Ganesh, has this if you start reading her other work. An awful lot of everything she's done seems to have characters in common with the Gearworld, her vaguely-steampunk clockwork-labyrinth art-and-fiction setting. It's only vaguely hinted at in Digger itself.
• Sugar Bits might have done it when one of the villains summoned Red and The Big Bad Wolf from Ever After to fight protagonists. However, given the nature of the Sugar Bits world and Bleedman's own words, those two comics may or may not share an universe and this will remain unresolved until Endling, creator of Ever After, will confirm it.
• Shaenon Garrity's Narbonic and Skin Horse were officially confirmed to take place in the same continuity with the introduction of Artie Narbon to Tip Wilkin. Garrity had previously revealed in Narbonic Director's Cut that the main Narbonic characters, Dave, Helen, and Mell, came from three different comics she had drawn in high school and college. Mell also gets her own Spinoff Babies comic, Li'l Mell, and a character introduced in that comic has now shown up in Skin Horse. Garrity's lesser-known Smithson may fit into the same continuity as well; minor character Queensbury Joe appears to be the older version of Homeschool Joe from Li'l Mell.
  • Mel has also appeared twice in Everyday Heroes - once in a brief flashback where Mr. Mighty thwarts one of Helen's capers and again where she appears as Dr. Unpleasant's lawyer.
• Eli Parker created several different web projects, including Too Far (a comedy space opera webcomic), Powerup Comics (a Stealth Parody of Two Gamers on a Couch webcomics), and These Web Comics Are So Bad (another Stealth Parody, this time of webcomic review blogs). Then Parker created Unwinder's Tall Comics, which included cameos from all of the above, establishing that they (or at least their fictitious authors) all exist in some sort of continuity.
• There was earlier hints about Bob and George and its fancomics/subcomics taking place in the same multiverse. Ridiculous amount of cameos got finally an explanation, when Rick O'Shay and Chick-Bot appeared in the main comic to tell the true nature of White Space. It was a demi-plane that connected all the universes together. It was later abused by sending all the Mega Mans and other characters into one universe, to fight Bob.
• Glorianna and Sparky of Lady Spectra & Sparky shared an adventure when Glorianna was briefly transported to the 21st century (while Lady Spectra ended up in Glorianna's era).
• Anna/Susan from Sire showed up in Evil Plan, where it was revealed that they are the cousin of Hero Antagonist Kevin Kolton. Characters from Evil Plan and Mortifer have shown up in each others' works, and Agent/Andrew Cross shows up in both Evil Plan and morphE.
• In Spinnerette there are a few arcs centered around Hell and its inhabitants, where we meet Minerva's friends Tom, Kia, Lucretia, and Guinness, all hailing from Krakow. Whether the Marilith duology and Charliehorse are also part of The 'Verse is unknown.
• Played with in the various Alternate Universe comics for Darths & Droids, where sources that aren't extensive franchises are sometimes "planned" to be continued with other works (either thematic or from the same creator) according to their FAQs. Of course, all of these comics are one-shots, and how these instances of canon welding could actually play out is left to the readers' imaginations. Now for the complete list of proposed merged canons...
  • Notes and Nazis (based on The Sound of Music):
    Will you do another movie after this?
    We're certainly thinking about it. We think the next logical candidate is My Fair Lady.
  • Sandals & Spartans (based on 300):
    Are you going to do something after 300?
    We plan to go on and do other films based on classical Greece. Disney's Hercules comes to mind as an obvious sequel.
    
    What about other parts of the classical world?
    Greek legend is so rich that we don't think we need to bring in anything else. I mean, just look at Xena.
  • Trenchcoats & Turncoats (based on Casablanca):
    Will you continue with another movie after Casablanca?
    We plan to do all of Humphrey Bogart's movies, as though they were a single connected campaign following the same characters. Next will be The Maltese Falcon.
  • Heists & Hypnagogic Hallucinations (based on Inception):
    What are you going to do when you finish Inception?
    We plan to do go on to other Christopher Nolan films. Memento and The Prestige seem like logical choices.
  • Chocolates & Chumps (based on Willy Wonka & the Chocolate Factory):
    Are you going to do any other Roald Dahl works?
    Yes! We're going to do some of his other screenplays. We plan to make a trilogy by scripting Chitty Chitty Bang Bang and then You Only Live Twice as sequels to Willy Wonka and the Chocolate Factory.
  • Hellenes & Harryhausens (based on Jason and the Argonauts):
    Are you planning to do any other Harryhausen films?
    Yep. We've planned a story arc through The 7th Voyage of Sinbad and the two other Sinbad movies, climaxing with Clash of the Titans!
  • Marmosets & Meerkats (based on based on David Attenborough's The Life of Mammals):
    Are you planning to do all of David Attenborough's nature documentaries?
    Yep. We've planned a story arc through all current documentaries from Life on Earth through to Conquest of the Skies!
  • Elliotts & Extraterrestrials (based on E.T. the Extra-Terrestrial):
    Are you planning to do any further movies?
    Yep. We've planned a story arc involving aliens which will continue with other Steven Spielberg films: Close Encounters of the Third Kind and then War of the Worlds!
  • Moonshots & Mishaps (based on Apollo 13):
    Are you planning to do any further movies?
    Yep. We've planned a story arc involving all the other films directed by Ron Howard and starring Tom Hanks: Splash, followed by The Da Vinci Code, Angels & Demons, and Inferno!
  • Pac-Mans & Power Pellets (based on Pac-Man):
    Are you planning to do any further video games?
    Yep. We've planned a story arc involving other classic games such as: Space Invaders, Asteroids, Donkey Kong, and Tetris!
  • Drivers & Dubble-yas (based on It's a Mad, Mad, Mad, Mad World):
    Are you planning to do any other Stanley Kramer films?
    Yep. We've planned a story arc involving several of his other films, including: On the Beach, Judgment at Nuremberg, and Guess Who's Coming to Dinner!
• Two of Doctor Glasgow's previous comics were folded into Ennui GO!:
  • Izzy's clone Kirsty and her husband Lucian are explicitly stated by Word of God to be the parents of the protagonist of his previous comic, Rainbow Skies Forever, but Word of God also states that Ennui GO! is an Alternate Universe.
  • Max, Min, Adelie, and Bella come from another old comic called Max and Min. One of its strips would even be recycled as "Avast", suggesting that it actually is canon rather than merely being an Alternate Universe.
• Characters from SgtCrisis' earlier projects make appearances in their comic, Big Break (2019). For example, two characters, Brett and Mira, were part of aGundam fan-project called "Gundam Attrition", where the former was a pilot and the latter an engineer. They were also a couple in that story. In Big Break, they both have been given more mundane jobs (i.e. Brett now owns an indoor pool business while Mira owns a gym.) and, while originally stated to be a married couple, the creators retconned their status as never having met in the comic proper.
• Harry Bogosian's Demon's Mirror and A BETTER PLACE are welded together in the former's ongoing rerelease. The rerelease's captions, which are its new content, are centered around firmly welding the two continuities together. It's unlikely that the latter was originally intended as a proper Stealth Prequel, because the captions do a lot of welding, and it's all still a little hard to buy.
• A arc of PS238 revealed that the author's previous work, Nodwick was actually set in PS238's distant past when time travel results in the protagonists from both settings encountering each other.

Web Original

• The (In)Famous David Gonterman, Ed Wood of the World Wide Web and the Internet's Most Dangerous Cartoonist; reuses characters, concepts and names so often that it more or less seems that every single thing he's ever written or drawn are all set in the same vague universe/multiverse. This may be partially intentional, but, well...
• The Fear Mythos incorporates The Slender Man Mythos into their canon, as well as the Black Dog from folklores of the British Isles, and later incorporated the Smiling Man from The Jeanette Experience as a Canon Immigrant. The Cthulhu Mythos is a part of it too, with the blog Mephi, having many of Lovecraft's creatures being a major part of the story. The Fear Mythos and Sleeper Mythos are also an example of this, while the Fear Mythos and The Arkn Mythos are an inversion (depending on who you ask, as the exact history of the latter is disputed and unclear). The Fear Mythos as a whole was created from several separate Slender Man Mythos spinoffs, then separated into countless canons as the authors of each story see fit.

Web Videos

• Dream SMP has done this on multiple occasions, most notably when Jschlatt confirmed that the older server SMPLive is at least partially canon, and when Nihachu confirmed that her character travels between Dream SMP and the otherwise unrelated Bear SMP.
• A YouTuber named PopularMMOs has a series called The Crafting Dead. In the third season, he puts Dr. Trayaurus of TheDiamondMinecart fame into the series. Before him, he puts Captain Cookie, from Epic Proportions, another series by the YouTuber, became part of the story.
• Channel Awesome likes this trope, finally creating an official merging of every TGWTG-involved character during the huge anniversary brawl, and again during Kickassia, Suburban Knights and To Boldly Flee, plus the millions of crossovers between producers. The Nostalgia Critic took this a step further and incorporated Doug himself into the mix, crossing over with his vlogs.
• This is a frequent occurrence for SMPLive retroactively, due to the creators moving on to new projects over the years and tending to enjoy connecting them.
  • Schlatt retroactively confirms that SMPLive is at least partially canon to Dream SMP in an episode of Tales from the SMP. This indirectly connects it to Bear SMP as well, and Minecraft Championship, both of which are canonical to Dream SMP.
  • It is also implied at some points during Epic SMP Season 2 that it's canon to that server as well.
  • In SMPEarth, it is noted that Wilbur's character wants to reform from his "dirty crime boy" ways on SMPLive, adding yet another layer.

Western Animation

• Disney, if you can believe it, did this.
  • Lilo & Stitch: The Series had Crossovers with Kim Possible, The Proud Family, Recess, and American Dragon: Jake Long. The Disney Channel Animated Universe was codified by these crossovers.
  • Recess' Ashley Spinelli appeared on Fillmore!, adding that show to the universe.
  • There was also an episode of Hercules: The Animated Series in which Jafar and Hades cut a deal to eliminate each other's enemies, resulting in an Aladdin: The Series crossover.
  • While DuckTales (1987) and Darkwing Duck were obviously (to the fans, despite Tad Stone's statement that they were supposed to be separate universes) part of the same universe what with both shows having Launchpad McQuack, a Disney Adventures story known as The Legend of the Chaos God establishes Goof Troop, TaleSpin, and Chip 'n Dale: Rescue Rangers are part of the same universe as well.
  • Gargoyles Word of God, Greg Weisman, says it shares its universe with Atlantis: The Lost Empire — or at least, each 'verse includes a Broad Strokes version of the other franchise. (This occurred when Weisman worked on an Atlantis TV spinoff — but the series, including the Gargoyles Cross Through episode, got canned when the movie bombed.)
  • The Legend of Tarzan features the villain Queen La; a native of Atlantis in the original Tarzan novels, the series gives her a character design that strongly implies that she is indeed an Atlantean, and that Tarzan (1999) shares a universe with Atlantis: The Lost Empire.
  • The Kingdom Hearts series of video games has most major Disney worlds—or rather, explicitly AU versions of them—existing in a larger multiverse.
  • Sofia the First is connected to the Disney Animated Canon due to appearances from Disney Princesses like Cinderella and Mulan, and even a bit of Pixar with Merida's appearances. Plus, characters like Aurora's fairies and Merlin also appear.
  • The DuckTales (2017) reboot is a new setting in which the pilot episode establishes that Cape Suzette and Spoonerville exist.
    • Darkwing Duck exists as a Show Within a Show but in later episodes, a fan of the series is inspired to adopt the identity.
    • From The Confidential Casefiles Of Agent 22! establishes that Adventures of the Gummi Bears took place somewhere in the Duck universe's past, as well as establishing that both F.O.W.L. and S.H.U.S.H. are actual organizations.
    • Quack Pack! introduces Goofy, who then goes on to show pictures of Max, P.J., and Roxanne, establishing Goof Troop and the two movies that followed as part of the continuity as well.
    • Later episodes also establish Chip 'n Dale: Rescue Rangers, Bonkers, and The Three Caballeros in this continuity, feature on-screen appearances of Cape Suzette, Don Karnage, and the grown-up versions of Kit Cloudkicker and Molly Cunningham, include the Phantom Blot from Mickey Mouse Comic Universe, reference Quack Pack in one episode, and add blatant, lawyer-friendly expies of characters from other Disney shows, including Gargoyles, Phineas and Ferb, and The Wuzzles, with even a reference to the above The Legend Of The Chaos God crossover!
  • Both Dana Terrace and Alex Hirsch have long implied that The Owl House and Gravity Falls share a universe. As of "Yesterday's Lie" this seems to be confirmed, as Eda is mentioned as using "Marilyn" as an alias in the Human World, the same name as Grunkle Stan's purported ex-wife, who otherwise matches Eda's description to a T.
    • The Owl House also seems to be connected to Amphibia given how Terrace and Matt Braly include easter eggs in their shows. This gains possible confirmation in the latter series episode "If You Give a Frog a Cookie", since Dr. Frakes' pictures of other dimensions includes a shot of the former series' titular location, albeit blurred. It was outright confirmed when the season 2 finale of Owl House displayed a news article about the events of Amphibia on a smart device with a partially obscured picture of Anne.
    • On another note, Amphibia and Gravity Falls are also in the same boat since "Wax Museum" is basically a tribute to the latter series and includes counterparts of Stan and Soos. There's even a cryptogram that when translated says, "There is a Soos in every dimension".
• Hanna-Barbera hit this trope super heavy to the point regardless of Continuity Snarl most people assume HB as a whole has a Shared Universe.
  • It can be said while there had been years of Shout-Out from Funny Animal to other Funny Animal, Yogi's Birthday Party was an end to Yogi Bear that not only featured characters from his own show and supporting shows but also from The Huckleberry Hound Show and Quick Draw McGraw.
  • There's a minor supporting character Bigelow Mouse had appeared on Snagglepuss, Yakky Doodle and Loopy De Loop.
  • When The Flintstones came along they got in on the fun too. Yogi even showed up in person in one episode (despite being name dropped as a tv show before). When the Flintstones went to the then-present Officer Dibble from Top Cat could be seen and when they went into the future it used the same design from The Jetsons.
  • Over in the action world the original Space Ghost cartoon ended with Time Travel and dimensional travel in the last six original episodes, became part of the same universe of, The Herculoids, Shazzan, Mighty Mightor, and Moby Dick
  • Then in the 1970s came along and Yogi's Ark Lark brought a good chunk of the Funny Animal characters together into one story including the ones from Top Cat. For good measure Sawtooth from Wacky Races was there and they ran into Moby Dick. This special was followed by Yogi's Gang.
  • When The New Scooby-Doo Movies came along, Scooby-Doo crossed over with multiple other HB shows such as The Harlem Globetrotters, Jeannie, Josie and the Pussycats and Speed Buggy. Although some had referenced each other before. Also Scooby met Laurel and Hardy who had a previous HB Animated Adaptation, the same voice actors from that show returned but they did give them an Art Shift to match the Scooby look more than the Yogi look.
  • Both The Addams Family and The Three Stooges (as The Robonic Stooges) got their own cartoon series following this series.
  • When Scooby Doo got another show that aired in the same block as Dynomutt, Dog Wonder, the Scooby gang showed up in three direct episodes of Dynomutt's show. Mumbly did likewise at the end of another episode. Even further in one episode where a singer sings the theme song from Jabberjaw.
  • In the last episode of Hong Kong Phooey we first meet Posse Impossible, who later got their own spinoff series on CB Bears.
  • Then came Laff-A-Lympics that established all those Funny Animal characters and those You Meddling Kids characters could compete in crossover Olympics. Captain Caveman and the Teen Angels and The Great Grape Ape were both newer and connected here for the first time. Guest appearances by Fred Flintstone and Barney Rubble as well as Jabberjaw helped seal that neither Celebrity Paradox nor Timey-Wimey Ball could affect this trope.
  • Then came Yogi's Space Race. Yogi, Huck and Jabberjaw were back now crossing over with new characters such as the other Galaxy Goofups and Buford and the Galloping Ghost. This series also provided cameos from the usual Fred and Barney, Grape Ape and Quick Draw. And the not as usual, Frankenstein Jr., Jana of the Jungle and the HB version of Godzilla from The Godzilla Power Hour.
  • There was also Casper's First Christmas which used Casper the Friendly Ghost and Hairy Scary from their previous Casper series Casper and the Angels meeting up with Yogi and other Funny Animal characters.
  • Then The Flintstone Comedy Show came along as tied Captain Caveman into having been alive in Bedrock before being frozen and revealed The New Shmoo was there too or at least one of his ancestors was.
  • Space Stars loved to play with crossovers bringing back Space Ghost and the Herculoids but also letting them meet up with new characters the Teen Force and Astro from the Jetsons. In one segment there's even a statute of Fred Flintstone in a museum for good measure.
• In the South Park episode "Super Best Friends", there is a brief scene of the cast of That's My Bush! in the White House, indicating that the two series (both created by Matt Stone and Trey Parker) take place in the same universe (which is particularly silly, since That's My Bush! is a live-action show). Another Comedy Central show, Dr. Katz, Professional Therapist, was also included in a brief bit from a season 2 episode with Mr. Garrison going for therapy (Dr. Katz ultimately gets killed by the giant firework snake).
• There were reportedly plans to weld the canons of Exo Squad and Robotech back when the former was produced. Considering that their primary motivation seemed to be that both shows were Merchandise-Driven, your mileage may vary on whether it's a good or bad thing that this never happened. It went beyond just planning; there were figures of Robotech mecha sold in Exo Squad-branded packaging.
• In a crossover episode, Stan and Bullock from American Dad! try to stop Family Guy's Stewie plan to take over the world, with Stewie mistaking Stan for Joe. Of course, this takes place in a virtual reality simulation, so it's debatable whether it's canonical or not. There have been a few other smaller cameos.
  • There is a deliberate lack of crossovers between Family Guy and American Dad!, but they're considered to be part of the same universe. However at the end of the American Dad! episode "Hurricane!", the houses of Cleveland and Peter end up on the sides of Stan's house, resulting in them going into a stand-off that ends with Francine accidentally being shot by Stan. It's never addressed in later episodes of any of the shows.
  • Thanks to the Family Guy episode "The Simpsons Guy", it can now be said that The Simpsons takes place in the same universe as the aforementioned Seth MacFarlane cartoons.
• Thunder Cats 2011, as of the episode "Legacy" features new versions of characters from SilverHawks and TigerSharks, all of which were action cartoon shows produced by Rankin/Bass in the '80s, sharing the same art style, writers, and voice actors. While the shows were incredibly similar and could easily be mistaken for being part of the same universe, it's only official now after twenty plus years.
• The Venture Brothers attempted to weld itself onto the Jonny Quest canon, even going as far as to feature Race Bannon as a character in one episode, but after Warner Bros. withheld the characters in anticipation of an unreleased live-action movie, all references to Jonny Quest were quietly replaced with Lawyer-Friendly Cameo versions.
• Rankin/Bass Productions is also famous for its adaptations of Christmas stories, and eventually welded many of them together in a movie called Rudolph and Frosty's Christmas in July. Naturally there were a lot of elements that did not quite fit together — Santa Claus, for example, had a subtly different appearance and personality in each previous special—so decisions and adjustments were made. Likewise some scenes from Rudolph and Frosty's lives were shown that differed from their own specials, but kept the basic facts the same.
• Originally Static Shock referenced Superman as a fictional character but this was retconned allowing the show to be welded into the DC Animated Universe.
• The Critic's Jay Sherman once showed up to judge the The Simpsons' Springfield Film Festival, though Matt Groening was so against the idea that he took his name off the opening credits for that episode. The welding is a bit awkward, since it's established that The Simpsons are a cartoon in Jay's world, but he appears twice more in Springfield.
  Jay: [in a straightjacket] It stinks! It stinks! It stinks!
  Springfield psychiatrist: Yes, Mr. Sherman. Everything stinks.
• The Transformers:
  • In the '80s, it was broadly hinted that the original cartoon shared a universe with the G.I. Joe: A Real American Hero cartoon, and not-quite-as-broadly that the same was true for Jem and Inhumanoids^note My Little Pony was close to being the same universe with a couple scenes scrapped from My Little Pony: The Movie (1986). This has been taken much further in the 21st century, where not only were the previous hints confirmed, but now every Hasbro cartoon from the time period has been stated to be part of the same universe, and every other Hasbro property exists within the Transformers multiverse.
  • Thanks to Hasbro acquiring the IP to the characters the Go-Bots, one of the Transformers franchise's most infamous rivals, are now part of the TF multiverse. Further, the official fan club's long-running comic storyline and some new toys mean that Hasbro has retconned the Go-Bots into being just another Transformers show, with the Go-Bots having their own universal designation (something reserved for actual TF series) and Gobotron being retroactively declared as an alternate form of Primus.
• Space Ghost has become a recurring character in the [adult swim] Universe currently consisting of Space Ghost Coast to Coast, Aqua Teen Hunger Force, The Brak Show, Perfect Hair Forever, Harvey Birdman, Attorney at Law, 12 oz. Mouse, and possibly Sealab 2021.
• Steven Universe crossed over with Uncle Grandpa; UG himself declared it to be a non-canonical, April Fools' ep. And at the end, he pulls out a checklist revealing he's visited Dexter and Dee-Dee, Blossom, Bubbles and Buttercup, the Eds, Billy and Mandy, Mac, Juniper Lee, the SWAT Kats: The Radical Squadron (!), Flapjack, and Finn, with Clarence next up. (SWAT Kats being included was kinda surprising, considering it debuted in 1993, before the Cartoon Cartoons, and wasn't originally for CN, but rather for sister station TBS back when they aired cartoons.)
• Word of God places The Avengers: Earth's Mightiest Heroes, Wolverine and the X-Men (2009), Hulk Vs., and Thor: Tales of Asgard in the same universe. We have Wolverine appearing as a member of both the Howling Commandos and New Avengers and the Mutant Response Division imprisoning Whirlwind, as well as one Wolverine episode being a direct sequel to Hulk Vs.. (However, contradictions do exist, mainly in the portrayal of the Hulk and which eye Fury's eyepatch is on.)
  • Word of God has also said that the X-Men would have shown up in Season Three had it not been cancelled.
  • The show's tie-in comic (which was written by the show's creators) blatantly contradicted this, showing versions of Scarlet Witch and Quicksilver that were nothing at all like their WATXM counterparts.
• In the Teenage Mutant Ninja Turtles (2012) episode "Trans-Dimensional Turtles", it's revealed that the 87 Krang is actually part of the Kraang gathering. He was kicked out for being an idiot. When Krang and the Sub-Prime meet, Krang is referred to as the Sub-Prime's cousin.
• The Simpsons and Futurama started out as Mutually Fictional, but then "Simpsorama" happened. The later Simpsons episode "Cue Detective" establishes that Bender is still on The Slow Path in the Simpsons' basement. Coincidentally, Simpsons episodes "Holidays of Future Passed" and "Days of Future Future" exhibited more traits of Futurama's depiction of the future (e.g. aliens living with humans on Earth) than in previous episodes depicting the Simpsons' lives in the future. There's still no explanation behind the differences in skin colors between shows, however.
• Owing to how Rick and Morty deals with infinite timelines and infinite universes, theoretically any work could exist in the same canon. A few works have taken advantage of this for a good cameo:
  • There's more than a few cameos in Rick And Morty that show it takes place in the same continuity as Gravity Falls. Rick and Morty has the mug and notepad Grunkle Stan lost in a portal popping out of one of Rick's, Bill Cipher popping up on a computer screen, and Bill's ally 8-Ball dead in the Detoxifier, while Gravity Falls: Journal 3 contained a silhouette of a Plumbus and a Zigerionon, as well as an encoded message left by Rick.
  • A couch gag in The Simpsons featured Rick and Morty burst into The Simpson's home, thus proving that they exist in the same multiverse. It culminates in an Overly-Long Gag involving the death of The Simpsons and them being brought back, very poorly, via cloning while Rick robs their house.
    Bart: No more guest animators, man!!!
  • Even My Little Pony: Friendship Is Magic isn't safe from these two. Pony Rick and Pony Morty appear in the background of Grannies Gone Wild where, unlike their cameo in The Simpsons, they thankfully didn't kill anyone this time. We hope.
• The LEGO Batman Movie (2017) takes place in a continuity that includes all of Batman's prior film appearances.
  Alfred: Sir, I've seen you go through similar phases in 2016, and 2012, and 2008, and 2005, and 1997, and 1995, and 1992, and 1989, and that weird one in 1966.
  Batman: I have aged phenomenally.
• Word of God stated that Milo Murphy's Law was in the same universe as Phineas and Ferb from the beginning, but the shows have become more closely joined as the former goes on, with the eventual reveal that Doofensmirtz is destined to invent the Time Travel technology that Cavendish and Dakota use.
• Ben 10 has one with The Secret Saturdays with the Ben 10: Omniverse episode titled TGIS where it was shown that Ben and Zak happen to be the same age. Previous hints had been dropped due to references made (mostly on Secret Saturdays) such as some of Ben's villains appearing in a criminal database in Secret Saturdays or Dr. Beaman frequently using the expression "Great Galvan Prime". Another episode of Ommiverse has expies of Cow and Chicken appearing as customers of an interdimensional Mr. Smoothie. Charlie Adler reprised both roles.
• Jellystone!: In addition to the many characters established as part of Hanna-Barbera's Funny Animal universe, characters like Jonny Quest and Shazzan, who were not originally comedy characters, reside in Jellystone as well.
• Young Justice
  • The fourth season had one with Green Lantern: The Animated Series In the episode "Encounter Upon the Razor's Edge!", Razer makes his return weilding the Blue Lantern Ring that came to him at the series finale. At the end of the episode, Razer combines both his Blue ring and his old Red ring into a new form where he wields the powers of both Rage and Hope before returning to his quest to find Aya.
  • The tie-in comic "Young Justice: Target" shows that the short DC Showcase: Green Arrow, written by Greg Weisman as Young Justice was, had occurred in Earth-16.

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