A crossover is a fanfic or other fan-created work in which two or more fandoms are combined in some way. Crossovers are an old story trope of fanfiction; as soon as fans started writing stories in multiple fandoms, they started crossing those sources together. In story notes, a crossover is frequently notated with an 'x', so a Star Trek story crossed over with Star Wars is sometimes written as ST/SW and sometimes written ST x SW.
Crossovers can be a love/hate topic among fans. Some fans adore the possibilities they bring, while others believe they are rarely written well - or are simply uninterested in reading about the characters in any fandom except the one they originate from. Fans will frequently make rec lists for well-written crossovers, or else post requests asking for crossover works from particular fandoms that they'd like to see combined.
Crossovers have also been the subject of numerous communities and dedicated events (such as fests or exchanges), so that crossover lovers can connect and share the works that they love to create and consume.
Premises for Crossovers
Crossovers may take place in many ways. In the most common form, characters from Fandom A may meet characters from Fandom B (i.e., a Stargate Atlantis story in which The Doctor visits Atlantis, perhaps with a Companion or two in tow). Crossovers can involve as many fandoms as the author(s) can juggle; there's no limit to the potential madness and creativity of the exercise.
A form that is most common in Harry Potter crossovers, but sometimes seen in other fandoms with canon orphans (or characters who can easily be made to be orphans), is the adoption fic, in which someone from another fandom (generally selected for their kick-ass qualities) brings up the orphan.
Many fandoms use canon incidents or devices to facilitate crossovers. Star Trek's canon holodeck can be used to introduce characters from any other fandom, and its time travel allows crossovers with present-day or historical settings. In Buffy fandom the first Halloween episode involved enchanted costumes which made the wearer take on the personality of the person depicted; in the episode these were generic characters - soldiers, ghosts, etc. - and the effects wore off at the end of the spell, but in fanfic the costumes are often used to give Buffyverse characters the personality and sometimes powers of e.g. a superhero, often permanently. This trope has been borrowed by many other fandoms. Doctor Who introduced the "chameleon arch" which turns Time Lords into normal humans with false memories, revealed only when they open a device that contains their memories; this is often used in fanfic to turn characters from other fandoms into Time Lords.
Canon deaths which involve the disappearance of the body are sometimes used as springboards for crossovers; for example, when Sirius Black falls through the Veil of Death some stories have him emerge in the universe of another canon. This trope is also common in Buffy fanfic since Buffy fell into a mysterious portal as she died; although she did not disappear, numerous stories show her as transported to other universes in the period between her death and resurrection.
Another way of crossing two fandoms happens specially in the cases of fandoms that have non-human characters or characters with extra abilities. In this case, a character from Fandom A, while still being themselves, turns out to be (secretly or not) a type of character from Fandom B. An example of this is a character who turns out to be an Immortal from Highlander or a Doctor Who Time Lord as mentioned above.
Some crossovers are almost subliminal, like cinematic Easter Eggs, briefly using e.g. a character or device from one canon in a story set in another, which may go almost unnoticed. They are occasionally seen in canon as well as fan works. For example, The Laughing Fish, an episode of Batman: The Animated Series, has a scene in which Joker tries to kill Batman with a wrench he grabs from a box that appears to have a partially-obscured Binford Tool label, a Home Improvement reference. Buzz Lightyear is imprisoned in a box with the Binford logo in Toy Story. There are numerous Star Wars references in the Indiana Jones films, such as images of the robots among the hieroglyphics found in a tomb. Similar minor crossovers are common in fan works.
Types of Crossovers
Fusions are a kind of crossover or AU where characters from one fandom (Fandom A) may be imported into the setting of another fandom (Fandom B). Fandom A characters may take on the roles of Fandom B characters (i.e., a Stargate Atlantis story in which John Sheppard is a Sith lord and Rodney McKay is a Jedi, like The Dark Side, by Astolat) and not interact with Fandom B characters at all, or only very peripherally.
Another type of fusion has a character from one fandom take the place of a character in another while retaining their original back story; for example, a story in which Doctor John Watson, a British doctor newly back from Afghanistan, ends up working in Princeton USA and finds a flat share with Dr. Gregory House, not Sherlock Holmes.
Crossover fusions with romance movies (An Affair to Remember, American Dreamer, You've Got Mail, etc.) have been written in slash forever, but for some reason, they're rarely considered crossovers; they're just considered AUs, perhaps because the romance movies rarely have a fandom following of their own.
A special case are crossovers between sources that share the same actor. These same-actor crossovers sometimes draw criticism for requiring more suspension of disbelief, and in the case of same actor pairings also for blurring the line between character and actor slash, especially in the past when RPS was less widely accepted. In some cases these crossovers even rate their own pairing names, communities and challenges.
In SGA fandom, a common crossover technique is to write a character of David Hewlett's (from a show other than SGA) in a romance with a character of Joe Flanigan's (also from a show other than SGA) - this crossover pairing is known as Hewligan, and can refer to a variety of pairings (i.e., Grant Jansky (Traders)/Pete Sherman (Sherman's March), Michael (Century Hotel)/Nick (Farewell to Harry).
Other examples include the pairing names Chlean and Winsullivan, which name the crossover ship of Dean Winchester (Supernatural)/Chloe Sullivan (Smallville). Another case is the characters played by Aidan Turner and Dean O'Gorman, who played the brothers Kili and Fili in The Hobbit (film series). Pairings include DarkHawk: Ross Poldark (Poldark) / Jim Hawkins (Return to Treasure Island), and Britchell: Bragi (Anders) (The Almighty Johnsons) /Mitchell (Being Human).
In other cases, two characters played by the same actor turn out to be the same person; for example Claude Rains from Heroes turns out to be the Ninth Doctor in disguise, or Ducky Mallard from NCIS is actually an older Illya Kuryakin from Man from Uncle. See also the Six Degrees of Jeremy Renner trope, in which all characters played by Jeremy Renner (Hawkeye in The Avengers) are Clint Barton in disguise, siblings, clones, etc. A canon non-crossover example is the case of the vengeance demon Halfrek in Buffy the Vampire Slayer, played by Kali Rocha who had previously played William's (pre-vampiric Spike's) love-interest Cecily. In a later episode it was revealed that Halfrek was Cecily; comics canon says she was already a demon when William was in love with her. One pairing of this type is sufficiently common to be named; "Barneswald" is James "Bucky" Barnes/Clara Oswin Oswald, since the same actress briefly appeared as Barnes' date in Captain America: The First Avenger while Clara is cononically reincarnated in many avatars throughout history.
Stories in which characters played by the same actor are mistaken for each other, or impersonate each other, are also common. For example, Nathan Fillion played the murderous preacher Caleb in Buffy, and author Richard Castle in Castle; a standard trope seen in most crossovers between the shows has Buffy characters attack Castle as soon as they see him, assuming that Caleb has somehow come back to life. In non-crossover canon much of the plot of Orphan Black revolves around repeated cases of same-actress impersonation or mistaken identity.
These themes can be inverted in stories in which different versions of the same character (portrayed by different actors or in different media) meet; for example, versions of Superman from Superman Returns and Lois and Clark: The New Adventures of Superman, Sherlock Holmes from Sherlock and Elementary, etc. Usually the explanation involves Alternate Universes. There is also the canon non-crossover case of the Buffy episode The Replacement, in which two different actors, Nicholas Brenden and his twin brother Kelly Donovan, play Xander Harris so that two versions of him can meet.
Another variant of actor crossover is a crossover between the fictional and "real" worlds, with actors meeting or swapped with the characters they play; for example, Jensen Ackles meeting Dean Winchester, Robert Downey Jr. swapped with Tony Stark, etc.
Same Name Crossovers
A common if somewhat unimaginative trope takes two fandoms which happen to have characters with the same name. "Obviously" they're related! An example is Scott Summers and Buffy Summers, and there are several stories where they are cousins or otherwise related. This can be stretched slightly by ignoring differences in the spelling of the surname - e.g. Jamie Somers (The Bionic Woman) is also related to Buffy, but a different branch of the family that changed the name slightly. There are stories where Samantha Carter (Stargate series) is related to Agent Carter (Marvel) or Sheriff Carter (Eureka). In several stories Sirius Black is related to Bernard Black. It's even occasionally extended to fandoms where characters have common first names, if the name is rare enough; e.g. Xander Cage (the XXX series) and Xander Harris (Buffy), and to names that just "sound right"; e.g. Luna Lovegood (Harry Potter) has a name that "sounds sexy", so she might be written as a Bond girl.
An alternative approach is to treat common names as a coincidence which results in the events of the crossover; e.g., Buffy and Scott happen to reserve rooms at the same hotel and the desk clerk somehow thinks they're married and ends up putting them into the same room (bed-sharing trope); or a message intended for the Watcher Bernard Crowley (Buffy) ends up going to the fallen angel Crowley (Good Omens). This approach is comparatively rare.
Common appearance and other traits have often been used as an excuse for a crossover; two canon characters are alike in some way (they have similar ancestry, have red hair, have the same accent, are fencing masters, etc.) so must "obviously" be related or share some common background. This is very common in Harry Potter crossovers, with numerous red-headed characters from other fandoms (most notably Willow Rosenberg and Natasha Romanoff) written as relatives of Lilly Potter, the Weasley family, or both, regardless of plausibility.
Another way of combining sources is to build on their use of common locations. For example, The Avengers Movieverse has probably been crossed with every TV show or film that has a contemporary New York setting, and Angel with Six Feet Under and other Los Angeles shows. CSI Miami has been crossed with Burn Notice, Dexter, and other shows with a Florida setting. Another example is Wholock.
Fandoms which draw on the same historical period are another source of crossovers. An example might be a crossover between Jonathan Strange & Mr Norrell and the Temeraire novels, since both are set in the Napoleonic wars. World War II crossovers are very common, especially with Captain America. For example, since Wonder Woman is now depicted as active since World War I there are numerous stories which envisage her teaming up with Steve Rogers during World War II, and the parallels between Rogers and Steve Trevor are often mentioned. All time travel fandoms are fair game for such crossovers, of course, as are those involving immortality, especially Highlander.
Same Creator Crossovers
In this type of crossover two or more works by the same creator, or from a common origin, are crossed even though this never occurred in canon. For example, the Sherlock Holmes and Professor Challenger series (The Lost World etc.) were both created by Sir Arthur Conan Doyle, but the series have no characters in common. Numerous authors have written stories combining them, both as fanfic and as professionally-written "continuations" of these series.
Often crossovers are an answer to the problem of a much-loved character who lacks a shippable partner in his or her source fandom, or else an answer for a writer who only likes one character of a popular pairing—like Methos, but not Duncan? Write Methos into another universe altogether! Certain characters seem to lend themselves to showing up in other universes; they are sometimes referred to as Little Black Dresses of fandom.
Using Official Crossovers
It's not unusual for two or more fannish sources to have crossover episodes or events in canon. Typical examples are comic company crossovers between DC and Marvel, like the JLA vs. Avengers mini-series, and crossovers between Batman and Judge Dredd, Predator, etc.
TV shows also do crossovers, especially ones made by the same production company or owned by the same network. Sometimes they are build as a shared universe from the start, even as part of the same franchise, while in others the crossover idea comes when both are already established. They may take the form of double episodes or just run in one of the shows. Some examples are:
- Same universe:
- Double episodes examples:
- Character from one universe showing up in the other:
- People from reality shows appearing as themselves in a fictional show:
In some TV series the official crossover implications are almost byzantine through a series of such overlaps, and tracked on fansites devoted to this phenomenon. Doctor Who and Torchwood are so intertwined that many authors and sites consider them to be a single fandom; The Sarah Jane Adventures also derive from the same canon, and stories that mingle canon from all three shows plus spinoff novels etc. are moderately common. The recent spin-off Class (2016) will probably be incorporated into this common fandom too.
Arrow and its spin-offs The Flash, Legends of Tomorrow, and Vixen are often entwined with each other, fans often nicknamed the universe Arrowverse, Flarrow, and Legends of Flarrow. When NBC cancelled Constantine, it allowed the CW to have an official crossover between the two and thus the others. The official crossover episode between The Flash and the CBS Supergirl pleased many fans as did Supergirl's move to the CW; which officially brought more news of more crossovers between all four shows. The Supernatural episode Scoobynatural (2018) was a Supernatural/Scooby-Doo crossover, largely animated, which seems likely to spawn a good deal of crossover fiction.
An episode of the Star Trek animated series was an adaptation of Larry Niven's story The Soft Weapon, and Kzinti (warrior aliens from Niven's work) subsequently became part of the Star Fleet Battles wargame universe.
Crossovers and Meta
Sometimes the point of a crossover is a contrast and compare of the fannish sources. A meeting in a bar between Duncan (of Highlander) and Buffy, talking about the pain of being a Champion, or between Methos and Krycek, talking about the fun of being morally ambiguous killing machines. Sometimes the point is even broader, such as commenting on the pain of being a black sidekick, as in Them Mean Ol', Low-Down, Lando Calrissian Blues, by Yahtzee, or the trials of being a fictional character popular in slash fiction, as in Support Group for Fan Fiction Characters: First Meeting, Slash Chapter by Cousin Shelley.
Some crossover fanworks become so popular they gain fandoms of their own. Examples are Rise of the Brave Tangled Dragons, Superwholock, Pooh's Adventures, Non/Disney, most Animash and Fallout: Equestria.
Writing a crossover has its own dangers, the difficulty lying somewhere between single-media and professional writing. I like to write them because they add a bit of spice to a story and provide a challenge. I rarely enjoy reading them, however, because they're often poorly done; the writer or editor can't handle one of the shows involved or doesn't know enough about it, one of the shows is sacrificed for the glorification of another, humorous crosses aren't half as funny to the reader as they seem to the writer and editor, etc. Barring copyright problems, even television has problems with crossovers (does anyone remember the Magnum, P.I. and Murder, She Wrote crossover, where Magnum looked like a raving idiot and Jessica Fletcher came off as a meddlesome old hag?). Crossover fiction can be written and written well, no matter how outrageous the crossover.
I _like_ crossovers. The idea of mixing a couple of universes can be really exciting if its done well.. But then I like almost anything that's done well. The only things I enjoy that are less than well done (and well-done is always my own opinion, of course) are things that directly hit my kink or things that are in a fandom I'm in the obsessive phase in.
I like crossovers when they're whole stories. When there's a reason for the characters from different shows to meet, and when they are all developed, and when then all learn or change as a result of the story, and especially when they learn or change as a result of encountering the other person/pair. If they're just there for window dressing, I get angry.
[snipped]So I think that a lot of the problem with crossovers is that they're not well executed, or not well thought out. That is, the author is often lazy, hoping that she can let familiarity and/or humor carry her, rather than doing the work to write a good story. 
Although I personally don’t like crossover fics, I understand why others might. That’s fine. The trouble is when I read blurbs that say Death Note x DBZ x Buffy x Star Trek: TNG x Dragnet x Entourage x Gilligan’s Island. Who in the world has seen all of those shows and is familiar enough with all of them to get your references? You are limiting your audience to very very few people. It’s the problem with in jokes. If only a few people get your in-joke, each of those few people will enjoy it A LOT. But only those few people. Everyone else will make a “buh-wha??!” face and click the back button on their web browser.
I love crossovers, I really do. I'm a sucker for them if I am at all familiar with the fandoms.
BUT it's so hard to find multi-chaptered ones that start out good and sustain the quality all the way through. Most of them fall prey to overloading.
Sometimes it comes from trying to shoehorn every single character from Universe A into Universe B. Sometimes it comes from trying to dump in Universes C,D,E, and F. Sometimes it comes from having all the in-jokes from both Universes crammed in at inappropriate places that interfere with the plot.
But here is one of THE most annoying: The author decides to pair Character Alice from Universe A and Character Bob from Universe B, no problem. Then she decides that all of Alice's friends must each be paired up with each of Bob's friends. It doesn't seem to matter how ill-suited they are, or improbable, or how OOC it makes one or both.Please, author, gives little thought. A Crossever is unlikely enough. Unless you are going for a parody, try to avoid overloading your reader's suspension of disbelief. And eventually, like nearly all such stories it will start to topple over from sheer weight, and like the vast percentage of such stories, be left incomplete.
I know the feeling, sometimes people seem to overdo it with pairings.
My biggest problem with recent crossovers though, is that people keep creating family connections between characters from separate shows, without thinking through whether those connections would make any sense or not.
Like, I may not like stories that have Tony Denozzo knowing the Winchesters prior to the story, but their childhood makes it believable. But when you try and claim that Tony 'is' a brother to Sam and Dean, that's a whole other thing, exactly because we know so much about Tony's dad and his childhood. Same goes for Harry Potter, or any other character who's parentage is pretty well known. (and not just because I hate the idea of forcing another Winchester sibling into the story, especially one that supposedly grew up with them)
So, anyone who knows me, knows I love crossovers. Now, I'm very particular with the type of crossover. I don't like completely AU crossover. For instance, Naruto and Harry Potter, where Naruto is not a ninja and Harry is not a wizard. They both own...hell, idk, bakers next door or something. I don't like those. I want a true crossover...where the actual stories are merged together, like Naruto got hired by Hogwarts to guard it or something. But that's just an example.
So...now we get to the reason why crossovers can suck...and in particular, the Naruto fandom (cry). Yall know I love Naruto...I mean seriously, I love those ninjas, but for some reason, when people think crossover, they immediately go into harem mode. WTF... I mean seriously, harems, left and right. If there is anythiing I hate in fanfiction, it's a harem.
I just had to vent this, because I'm currently on a crossover desiring binge and I keep getting screwed over with all the harem bs. I'm very broad in my various fandoms, so it's not over hard(I say that loosely since there aren't that many crossovers out there compared to various fandoms), but I get by. THe problem is that when I see a particularly rare fandom used in a cross over and I like that fandom, I get excited and then I see the dreaded word, harem and I almost cry and cringe and want to ask...why?Why are harems so prevelent in crossovers compared to singular fandoms? I don't understand it.
I love crossovers more than I love regular fics, purely for the potential they represent. Crossovers are basically how people write original fiction. "Ok, so I'm going to take guys from Book A and put them in a situation from Book B and suddenly I've got something entirely different! WHERE DID THOSE FLYING MONKEYS EVEN COME FROM?!"Seriously, I love crossovers. When you get two universes that work well together, they work really well together. And for universes that are only somewhat compatible, you can have tons of fun figuring out how to mesh the two together. It's great when two people from different books have entirely different skill sets but similar power levels, because both of them can pull all sorts of aces out of their respective hats that the other person has never even dreamed of. Really gives you a lot of wiggle room when writing a story.
The reason why crossovers are my favorite type of fanfiction, is because the clashing elements of both respected universe. I love to see the ripple effect of foreign forces and how it effects the main characters and the world around them. Especially if a main character from universe 'A' has powers or a technology that is unknown in universe 'B', it usually deviates the plot in a slightly new, if not completely new direction.
I've had a select few crossover fanfics send a chill up my spine which would make prefessional authors pale in comparison.
I would say the reason why many people hate the idea of a crossover, is because its either unrealistic or it was performed poorly or it has more than two universes involved the crossover. And I can see why people would hate crossovers from that perspective. I personally hate any crossover that involves 3 or more universes, it's almost always done poorly and it involves to many assumptions on the readers knowledge on the background of each and every universe.BUT! If you put those bad thoughts aside and search through a plethora of fanfiction. I guarantee that each hater of this genre would find an awesome clash of two of their favorite series and fall in love with it. Even if it's just one fanfic, there is unlimited potential in this category.
I don't often get into crossovers because, not being familiar with a whole lot of popular games or shows, I don't usually know both halves of the crossover. Every now and then I can make an exception and enjoy something that's unfamiliar to me, but I usually find it too frustrating and confusing.
When I first started reading Spuffy fanfic, I scorned the idea of crossover fics. I wanted to read about my favorite show and my beloved characters and no one else. Now I know, that there are gems to be found in crossover fics. If crossovers are your cup of tea, I highly recommend the fanfic site Twisting the Hellmouth, which is solely devoted to Buffy crossover fanfics. You will find every kind of crossovers there - Buffy with Harry Potter, Buffy with Dean and Sam from Supernatural, Buffy meets Dr. Who, and even Buffy and Mr. Darcy.
Crossover Filtering on AO3
In 2018, AO3 rolled out a major update to its searching and filtering functionality that included the option to filter for or exclude crossovers - which was a source of excitement for crossover lovers and haters alike.
Thank you so much for the hard work! The crossover exclusion is one of the things I've been looking forward to. I'll be tinkering with the options now.
Everyone else has already given all the kudos for the ability to exclude tags (yay!), but allow me to express my excitement and gratitude for the option to show only crossovers! For when I'm in the mood for a Labyrinth (or MfU or Highlander or, or) crossover but don't care what it's crossed-over with! It really helps give the smaller fandoms and obscure crossover choices some love \o/
Examples of Crossover Fanworks
- For a full listing of Crossover fanfiction on Fanlore, see Category:Crossover Fanfiction
- A pre-internet crossover is A Meeting in the Hyades by Marion Zimmer Bradley, in which Aragorn from The Lord of the Rings appears in an early version of Darkover; first published in 1961 but written in the 1950s.
- An example from 1954 - Dorothy L. Sayers wrote The Young Lord Peter Consults Sherlock Holmes for the BBC's Radio Times magazine.
- One of the earliest online multifandom crossovers was "The Witness" by Michele Martin, which crossed X-Files, Forever Knight, Highlander, Starman (tv), and Quantum Leap, along with several cameos from other fandoms. It was archived on Gossamer on May 16, 1995.
- Wherever You Stand A Hundred Shall Fall by James Walkswithwind is a Batman/Sentinel crossover ~ 1996-7
- When Hellmouths Collide by Kimberley Rector and Martha Wilson is a Buffy the Vampire Slayer/Hercules: the Legendary Journeys crossover. (1999-2002)
- Donna the Vampire Slayer by Nomad (nomadicwriter) is a Buffy/West Wing crossover, the first of a trilogy (2001)
- Them Mean Ol', Low-Down, Lando Calrissian Blues is an influential humorous multifandom crossover by Yahtzee, highlighting the underutilisation of male characters of color in popular television shows (January 2002)
- Hell Money by FayJay is an early example of Buffyverse/Smallville, which would prove a rich crossover playground (May 2002)
- The End of the Beginning by Mariner is a popular early Buffyverse/Harry Potter crossover (2003)
- Laura Mason's "Wrightsville: Long Ago and Far Away" is a crossover between The Charioteer and Ellery Queen (2006–7)
- Professor Doyle by Lucinda uses the canon death and disintegration of the popular Angel character Doyle to propel him into the Harry Potter universe. Angel/Harry Potter (2006-2017 WIP)
- Dust in the Wind by Lyra_wing was a SPNxAmerican Gods story (March 2007)
- And All the World Beneath by Seperis was a famous SGAxSPN story (August 2007)
- Supersaturation by SkoosiePants is SGA/Bandom (2007–9)
- "House of Cards" by nevoreiel and "Escape from Solitude" by mysid are crossovers between Torchwood and Mary Renault's novel, The Charioteer (2007 & 2010)
- The Eighth Weasley by Fyre (2001-8) is an example of the "shared trait" type of crossover, in which Willow Rosenberg is a long-lost member of the Weasley family.
- Angel, Dr. Horrible's Sing-Along Blog: In Memory of Penny Lesse by Jedi Buttercup. Just when you feel you've almost drowned, you find yourself on solid ground. (2008)
- "You Are Cordially Invited" (and its sequels) by fawatson is a futurefic crossover with characters from at least four modern novels by Mary Renault (April 2008)
- The Kingdom of the Blaggers by Hackthis is a crackfic fusion: "The problem with being the son of Uther Pendragon, legend of stage and screen, winner of Emmys (twice), Tonys (once), Oliviers (multiple), BAFTAs (twice), Oscars (once) and People's Sexiest Man (twice) was that nobody was ever going to take Arthur seriously as an actor in his own right." (2009)
- Labyrinth, Pan’s Labyrinth: A Lost Child in a Forgotten Tale by amelia_petkova. Ofelia wishes her brother away but not for the reasons you might think. (2010)
- "Confidence Lost" is a 33-chapter Batman/White Collar crossover by C.R. Scott (2011)
- Buffy, Teen Wolf: Botched by Rivulet027. Derek botched Dawn’s rescue attempt or Dawn botched Derek’s rescue attempt. Either way Stiles and Isaac rescued themselves. (2012)
- The Avengers Movieverse, Doctor Who: Make It Your Strength series by kerrykhat. "I'm Doctor Martha Jones," she told the pale man in the black, gold, and green armor who had invaded UNIT. "Who the hell are you?" (2012 – now)
- The Avengers Movieverse, Hansel and Gretel: Witch Hunters: By Any Other Name by [Liannabob]. "A Clint/Hansel mindswap fic with a whole lot more plot than that statement might imply. I mean, lots of crossover shenanigans, of course. But also a plot." (2013)
- Superman Returns, Lois and Clark: The New Adventures of Superman: The Planes by Dandello. "When Superman and Lois are thrown into a world where Clark Kent is EnC of the Daily Planet and married for ten years to Lois Lane, things get more than a little strange for both sets of Lois and Clark." (2006-7)
- Harry Potter, Stargate SG-1, Buffy, Batman, The Bionic Woman, The Secret World of Alex Mack: The League of Extraordinary Women by Diane Castle. "Hermione Granger has to recruit six women to help her stop an army of monsters before her world is overrun. But none of the women are even in her dimension…" Start of a series now running to nearly two million words, taking in dozens of fandoms, with "side stories" by at least nine other authors.
- Sherlock, Elementary: Elementary, My Dear Sherlock by Eltuine. "Joan Watson wakes up in an unfamiliar house in an unfamiliar city, with an unfamiliar man staring at her, claiming to be Sherlock Holmes. Meanwhile, on the other side of the ocean, John Watson finds himself in a similar situation. When each Watson tries to return home, however, difficulties arise. How will both Sherlocks deal with the removal of their respective Watsons, and how will each Watson get back to where they belong?" (2013- WIP)
- Star Trek: The Next Generation, Buffy: Legend by Shayne Terry. "Trapped by an alien collector, Lieutenant Commander Data discovers an early 21st century android excavated from the ruins of Sunnydale and a capsule containing the frozen body of one of the Eugenic wars most notorious figures...Buffy Summers." (2011)
- Young Wizards, Callahan's Bar series - Spider Robinson: Callahans by Avida calandia. Considering the precedent set by our predecessor, Callahan’s Place, we should’ve known it would only be a matter of time before something strange and wonderful walked in. (2012)
- Buffy, X-Men: Buffy and the X-Men by Plato: Buffy runs away to New York instead of LA in hopes of starting a new life. (2003)
- Mr. Benn, The Invisibles, RPF: Mr. Benn: Invisible by dontmakeeyecontact. When Jack Frost and Jolly Roger find they need to break into a record company’s impregnable headquarters they call upon the help of a singular individual. Crossing a popular British children's cartoon series of the 1970s with Vertigo's The Invisibles and rock RPF. (Date unknown)
- Doctor Who, Nero Wolfe: The Orchid Thief by leviathan: Nero Wolfe and Archie Goodwin have solved a lot of tough cases in their careers as detectives. But never one like the one that begins with the new arrival in the Plant Rooms. Before it ends, they'll deal with a tattooed lady, miniaturized corpses, and Things from Another World! (2009)
- Addams Family, Angel: Her Beauty and Her Terror by ijemanja: Amanda Buckman moved to California, changed her name, and became a vampire. Wednesday can't help but approve. (2007)
- Buffy, Avengers, Supergirl: Origin Story by Worldmaker: Halloween ends, and Xander finds himself in a place he never thought was real, under circumstances he never saw coming. (2013-2016 WIP)
- Harry Potter, Black Books: Noble and Most Ancient by Nomad (nomadicwriter): Bernard's past catches up with him - by owl post. (2013)
- Harry Potter, Doctor Who: The Rising Storm by TardisIsTheOnlyWayToTravel: Harry Potter opens a fob watch, and his life and destiny is changed forever. (Story series, 2014 - now deleted, link via webarchive.org)
- Doctor Who, Sherlock: Blurred Lines by Dont_call_me_Carrie: In one life, Martha Jones left the TARDIS, helped her family pick up the pieces, moved on with her life, and later got married to Mickey Smith. This is not that story. Or, Martha Jones replaces John Watson. Cue divergences. (2016- WIP)
- Immortal Women, a Highlander/Forever Knight crossover by Lynn Levine.
- Biomass Effect, a Mass Effect & Prototype crossover fic by Beastrider9.
- Breaking the Chains, a The Professionals and The Scarlet Pimpernel slash fic from 2004
- do you believe in soulmates (because I'm yours and you're mine) by geralehane, a The 100/Fear the Walking Dead crossover involving the fanon crossover character of Elyza Lex. (2016)
- Sherlock, Harry Potter: Fan Art: Transcendental: a Harry Potter/Sherlock Crossover (2016) by ObsessedtwibrarianOTB, cover art for a fanfic
- Tommy - The Who, Harry Potter: Pinball Wizard (2015) by Lovcats, Tom Riddle as Tommy.
- For a full listing of Crossover vids on Fanlore, see Category:Crossover Vids
- Star Wars, COPS: Troops (1997) written/directed by Kevin Rubio, a fan-made and acted video based on the Tatooine scenes from Star Wars: A New Hope
- True Blood, Queen of the Damned: Drink Me (2012) fan mix by Bironic - "The power of the blood of the First."
- Multiple Fandoms: Starships! (2012) fan mix by Bironic - one of the most famous fan mix videos, fusing scenes from dozens of science fiction sources into one music video.
- Night at the Museum, Hannibal, others: Night at the Museum Crossover (Fanvid Edition) (various dates) by Pheeby - a series of fan mix videos combining Night at the Museum with other fandoms.
- Inception, Team America: World Police: Team Inception: Dream Police (2010) by Matt Shapiro - Team America video with soundtrack from the Inception trailer.
- Pirates of the Caribbean/The Hobbit: Hobbits of the Caribbean: On Stranger Tides by Itar94 - "Parody crossover trailer made by adding Hobbit clips (AUJ+DOS) to the soundtrack of the official PotC: On Stranger Tides trailer. Not serious at all"
Example Art Gallery
Alex and Desmond by neofox (2010) (Assassin's Creed/Prototype)
Thematic Lists for Crossover Fic
- List of Forever Knight crossovers by fandom
- List of Starsky and Hutch crossovers
- Recs tagged crossovers/fusions at Fancake
- Star Trek/Sherlock crossovers: works tagged treklock at AO3
- The Professionals
- Same Actor Crossovers (response to Lucy Gillam), Shomeret at The Fanfic Symposium (1999)
- Any *NSYNC/XF crossovers????; archive link (April 2000)
- The Ten Commandments of Crossovers, Lucy Gillam at The Fanfic Symposium (2001)
- Crossovers, Kadorienne at The Fanfic Symposium (2002)
- Crossovers - shared_wisdom, Archived version Jane Davitt, (2008)
Communities & Events
- crossover_news: A fannish newsletter for crossovers
- Crossoverfic.com: An automated archive for crossovers that went offline in mid-2010
- crossoverfans: A Livejournal community for fans of crossovers, active from 2010-2016
- Crossover Fan Fiction: A LJ community "dedicated to authors and readers of crossover fan fiction"
- Twisting the Hellmouth: A dedicated archive for Buffy the Vampire Slayer and Angel crossovers
- Wormhole Crossing: A dedicated archive for Stargate crossovers, offline since early 2015
- In 2004, the Crossover Awards were established to recognize the crossover genre. The 2004 Winners are archived here and the 2005 nominees are archived here.
- Crossover Galore Challenge: A LJ community for crossover fanfiction from a variety of fandoms. Only one or two word prompts were accepted. It ran for 13 challenges between 2007 and 2012.
- Crossover Big Bang: A multifandom Big Bang challenge for crossovers with a minimum word count of 15,000 words, hosted from 2011 to 2013.
- Crossovering: A multi-fandom crossover exchange, hosted annually from 2014-2018.
- When Star Wars and Indiana Jones Collide: Attack of the Easter Eggs
- Lucy Gillam. Joxer?! And Other Things I Don't Get. Posted 24 November 1999. Accessed 3 October 2008.
- The Hewligan Fiction Archive; The Hewligan Fest community.
- Winsullivan and Winchullivan
- Poobala.com's Crossover Spin-Offs Master Page
- Them Mean Ol', Low-Down, Lando Calrissian Blues - Yahtzee
- "Support Group for Fan Fiction Characters: First Meeting, Slash Chapter" by Cousin Shelley
- from Psst... Hey Kid, Wanna Buy a Fanzine? #1
- comments by Megan Kent, from Virgule-L, quoted with permission (October 20, 1994)
- Why I’m Not Going to Read Your Fanfic by Seth Mlawski, posted on overthinkingit.com
- Crossovers by dreamflower02 via fanficrants, Livejournal. Published February 3, 2016 (Accessed January 16, 2021).
- Comment by liliaeth, posted February 3, 2016 (Accessed January 16, 2021).
- Crossovers... by Daydreamer1979 via Livejournal. Published January 25, 2017 (Accessed January 16, 2021).
- "Fan commenting on the post Why do you like crossovers? posted September 12, 2017 at r/FanFiction". Archived from the original on 2020-11-08.
- "Fan commenting on Opinion on crossover fics? posted July 20, 2018 at r/FanFiction". Archived from the original on 2020-11-11.
- flow's Spuffy fanfiction recommendation list by flowspuffy, 2019
- Comment by nimblermortal, Releases 0.9.210 - 0.9.217: Change Log, Archive of Our Own. Posted July 4, 2018 (Accessed November 9, 2020).
- Comment by deleted account, Releases 0.9.210 - 0.9.217: Change Log, Archive of Our Own. Posted July 4, 2018 (Accessed November 9, 2020).
- Comment by columbaria, Releases 0.9.210 - 0.9.217: Change Log, Archive of Our Own. Posted July 6, 2018 (Accessed November 9, 2020).