Sailor Earth / Anime & Manga

• Aria the Scarlet Ammo focuses on a paramilitary academy where students are taught to use guns, stunt drive, collect information. It's very easy to create a student for that.
• Attack on Titan focuses on the 104th Trainee Corps, so there are plenty of characters hailing from past Trainee Corps who have survived to the present time of the story. Information released also indicated that there are North, East and West batches of trainees apart from the South batch (which is the focus of the story), and since the top 10 students are from each batch rather than from the entire 104th it is possible to make characters join the elite Military Police and claim they're not from the South 104th, to make up for the 30 trainees who aren't seen.
  • The Stationary Guard/Garrison's massive numbers compared to the other military branches makes space for a lot of characters in various brigades or divisions.
  • Can't forget the Titan Shifters. They usually have unique traits like the Shifters in the story, and either are for humanity or against humanity.
• The premise of Black★Rock Shooter makes it very easy to come up with one. Every person in the world, or at least every girl, is implied to have an Other Self in Otherworld, and so all fans need to do is fill in the blanks. A new person, usually a girl, easily gets shoehorned into Mato's school as a new student (or employee) with some sort of Angst and the corresponding Other Self, or the fan just dreams up their own Other Self. In addition, the existence of White Rock Shooter practically begs for the creation of various copies and Expies of the eponymous character.
• The number of unused Three Kingdoms or even Dynasty Warriors characters in BB Senshi Sangokuden, coupled with the immense amount of leftover Gundam mecha provide prime fodder. Xiao Qiao Methuss, Cao Zhi Airmaster, Cao Ren Leopard...
• Bleach:
  • Since only a small fraction of the seated Shinigami officers have been revealed in the Canon, it's easy to introduce new characters, especially in the less-known divisions like the first, the seventh, and the tenth.
  • This also applies to the numbered Arrancar. 110 of them exist, but only about 20 of them have been shown, much less named. The novel Bleach: Spirits Are Forever With You by Ryohgo Narita takes full advantage of this.
  • There are also the rare Visored Sailor Earth, Quincies who thought they were the last of their kind before meeting Uryu, humans like Chad, or other types such as variations of Quincy powers (since there's an entire world to explore and Bounts could possibly not be the only spiritually-aware humans), or other types of people with Kido-Shinigami powers like Orihime and Hachi. Of course, these people are often very rare — possibly because these types are often rather harder to do than simply naming one-self as a seated officer or Arrancar who wasn't introduced.
  • Rarely, one may actually have a Bount who wasn't rounded up by Kariya.
  • The extreme ease (in both canon and filler) at which it seems anybody (regardless of whether they appear to be obviously the wrong age) can transfer into Ichigo & company's high school makes it that much simpler to introduce such an OC into the main characters' circle of friends.
  • Bleach fanfic writers also tend to enjoy adding in a "14th Division," which allows them to make their OC a captain without killing off any of the existing ones. Oddly enough the Kido Corps (which was revealed in the Turn Back the Pendulum arc to be something akin to a "14th Division" in canon; though technically outside the Gotei 13 it still answers to the Central 46 and the Captain-Commander like the 13 Divisions do) rarely gets used, even though its missing Captain and Lieutenant never had canonical replacements introduced, none of its current membership have ever been named or even had their faces revealed, and the Corps has a secretive nature that gives writers a blank check for its inner workings.
  • And now there are Fullbringers, humans who can have any power because their mothers were attacked by Hollows while they were pregnant with them. This is a blank check for any fanfic writers.
  • The final arc introduces the Vandenreich who are revealed to be Quincies. Their powers are far more diverse than what we had seen of Quincies so far, which opens up fan fic writers to think of their own abilities. However, as each member of this group has their power and epithet indicated by one of the letters of the English alphabet (known as a Schrift), one would either have to get Seussical with their letters or resort to a different alphabet entirely (as was the case with Shaz Domino, who is designated with Σ), as all 26 letters are already accounted for and only two letters are shared by multiple people (Y belongs to a set of identical twins named Loyd and Royd Lloyd and A was bestowed by Yhwach upon his intended successor, Uryu Ishida).
  • There's also the nobility of Soul Society. Of the Five Great Noble Families, only the Kuchiki, Shihouin, and Shiba clans have even been named, and each only has two currently-living members revealed during the course of the story. The lesser nobles who are subordinate to the Great Families are even more of a blank slate, with the only information about them being that roughly a quarter of the captains and lieutenants come from these clans, the Ise Clan being one of said clans. The New Captain Shusuke Amagai arc additionally introduces the Kasumioji Clan, a high-ranking family said to be just below the Great Families in terms of prestige and something of an anomaly in this regard. Since nobles have much greater spiritual power than the average Soul Society resident and are far more likely to achieve Shikai and Bankai, this leaves plenty of room to quickly establish a newly created Shinigami as being a big deal even if they're fresh out of the Academy. It also potentially gives them access to special power-boosting relics.
• Creating an OC for Bungo Stray Dogs is as easy as taking your favorite writer, and giving them a superpower named after one of their books.
• New Card Captors with either their own Clow Cards or another set of Cards in Cardcaptor Sakura. They tend to ignore the canon facts that 1. the Cards were a new form of magic invented by Clow; and 2. the Final Judgment couldn't take place until all the Cards were sealed. This fanon aspect would later be made canon by the existence of the Clear Cards in the sequel series.
• A Certain Magical Index and A Certain Scientific Railgun:
  • There are canonically millions of espers in Academy City, ranging from Level 0 to Level 5 (and a theoretical Level 6), leaving plenty of room for OCs. While there are only seven Level 5 espers, it's still possible to add an eighth one, and Aihana Etsu (the sixth Level 5) is still almost a complete mystery. There's also the concept of Gemstones, espers who are born with their powers unlike most espers, allowing for esper characters outside of Academy City.
  • There are even more magicians, and magic in the series can be based on any religion or other belief system (including recent ones like the Cthulhu Mythos).
  • Finally, there's the possibility of new right hand users. There are canonically three of them, each of whom has a unique power, so basically any power is possible.
• Chainsaw Man has Devils, monsters based on fears: the more common the fear is, the stronger the Devil (so Primal Fears like darkness and death are the strongest, while Absurd Phobias like tomatoes are weaker). Anything scary that hasn't been seen yet can easily be turned into a fan-made Devil.
• Chobits fandom is rife with extra Chobit-like persocoms, either as actual extra Chobits.
• Given the Claymore system of ranks and the fact that we haven't seen all of them, it's easy to imagine a Claymore who hasn't been seen yet filling one of the vacant numbers.
• Code Geass has the Britannian Royal Family. With 108 consorts, each probably having 1+ child to their name, it is not hard to fanfic writers to fill in the oh-so-loving household with original characters to have around. Either to make the family more human... or to give Lelouch C-List Fodder for his revenge when you run out of canon ones you want dead and it isn't quite time to kill Charles yet. For some context if we try to follow the numbers Lelouch had at least 10 older brothers as the 11th Prince, and 16 ahead of him as the 17th in line to the throne. We only know five siblings older than him/ahead of him in succession (the first and second Prince and Princesses, and the third Prince, as the third Princess Euphemia is younger than Lelouch). Two Princesses a bit farther down (possibly due to having been removed from the line of succession for the time) in Nunnally and Marrybell are the 87th and 88th in line. As implied, there are a lot of open character slots.
• D.Gray-Man:
  • Because the series only focuses on the activities of Allan's small group of Exorcists and a few Generals despite the Black Order having multiple branches across the world, it's not unlikely for people to create more Exorcists from those branches. Generals are included into the mix. Also, because of the lack of a recruitment age for Exorcists, many of them and some Generals tend to be implausibly young for the job.
  • It doesn't take much imagination to come up with an Exorcist either. In general they need a weapon (usually a cool one — Sinister Scythes are popular) and an experience with Akuma before being recruited.
  • When a new type of Innocence was introduced, many characters swiftly took on that type despite not having a lot of information on it at first, only based on the knowledge that the base two types of Innocence can transform.
  • Any new Noah is guaranteed to have their own ability/ies and usually highly sadistic and attractive since it's not stated how many Noah there are total. Anyone normal-looking can turn out to be a Noah.
  • Thanks to The Reveal about Allan and his connection to the Noah, there are inexplicably quite a few half-Noah Exorcists hanging around even if it's stated that Noah hate Exorcists.
• Death Note has Wammy's House, with 26 letters (or the combined total of all alphabet letters) of Sailor Earth goodness, for your crazy detective needs, usually a crossover of copies of L or other canon Wammy attendants.
• Digimon:
  • Any given series has a group of kids with Mons and Digivices, so generally it's a simple matter of picking a partner mon and a Digivice colour. Bonus points if the Digimon partner is entirely made up.
  • For Digimon Adventure, which already had an arc searching for a Sixth Ranger dubbed the Eighth Child, Sailor Earths often pop up under the title of the Ninth Child or higher.
  • This is easiest in Digimon Adventure 02, which had a whole "World Tour" arc introducing kids with Digimon partners from outside Japan, and had the last episode state that, by the time of the Distant Finale, every single person on Earth has a Digimon partner. Also, once upon a time there was at least one multi-author Fan Verse solely dedicated to 02 and the exploration of this trope in conjunction with Elsewhere Fic.
  • Also rather easy in Digimon Tamers, in which they could have been another tamer whose wishes were granted, or their partner Digimon actively sought them out.
  • Digimon Frontier:
    • There are four (potential) Sailor Earth positions to be filled: the four remaining Legendary Warriors. You know, the Psycho Rangers from the first half who never made a Heel–Face Turn? At least one fanfic has their spirits given to humans (in this case, all four of whom are somehow related to the heroes from Adventure/02). Alternatively (and as per a popular fan theory), the four remaining Spirits go to Katsuharu, Teppei, Chiaki, and Teruo, four other kids also called by Ophanimon to the Digimon World for the same reason as the Six-Man Band. With Chiaki as the sole female of the four, the gender ratio matches up perfectly with the vacant Spirits.
    • The fact that Advanced Hybrids do exist for Izumi, Tomoki, Junpei and Kouichi (JetSilphymon, Daipenmon, RhinoKabuterimon, and Reichmon respectively) but never got to be used, opens the door for Day in the Limelight Interquel chapters to showcase them.
  • Digimon Data Squad fics tends toward new members of DATS; it helps that it's mentioned in passing that other DATS units operate around the world, including the Austrian one Touma came from early in the series, so filling the gaps in in those is pretty easy.
  • Digimon Fusion fics generally involve the creation of a human general, a lead partner Digimon, and an accompanying Digimon army, though there's no indication that other human-led armies operated at any time during the war against the Bagra Empire. Digimon Xros Wars: The Young Hunters Who Leapt Through Time offers a more solid foundation — it's clearly mentioned that Digimon Hunting is something of a sport with many participants, so having another Hunter is pretty believable.
• DinoZaurs:
  • Take any creature that's been extinct long enough to leave fossils, give it a robot mode and a favored weapon, and play a news report where Kaito will see it about paleontologists finding a complete skeleton. You've now created a brand new Dino Knight.
  • Bringing in a new human is even simpler; give them a Dino Dagger. That's literally all there is to it. They might find it themselves, or they might be handed it after promising to be a Secret-Keeper; all that matters is that they have the Dagger.
• Dragon Ball: It is very easy to create a Saiyan without disrupting the universe's canon ^note it's simply a matter of saying "one more infant slipped through the cracks the same way Goku did" or "one more adult barely survived the purge of off-planet squads like Bardock, but this one didn't rush out to confront Freeza and get himself killed" — so much so that the 2008 OVA turned "Vegeta has a long-lost sibling" into Ascended Fanon and introduced said sibling as a character. Other categories of Sailor Earths include Dr. Gero's creations (he sealed a number of them away as incomplete and/or failures, a plot point also taken advantage of by one Non-Serial Movie and one video game), Namekians (or any other stripe of alien — DBZ has a lot of them), and even the occasional Earthling (though not as popular, since they Can't Catch Up). Dragon Ball Super takes it several steps further with the introduction of other universes, of which several out of twelve have been shown in varying lengths. In Universe 6, alone, the Saiyans continue to thrive, and that's to say nothing of the other universes that haven't been explored or shown only glimpses of such wonders as Super Sentai-esque Pride Troopers of Universe 11 whom an OC could easily slip into. In addition, Universe 6's status as a mirror to Universe 7/canon means that Universe 6 aliens can be used as OC bases in Universe 7, such as the lava-powered robot-like Metalmen. In addition as Universe 6 humans, Namekians, and other races from the main universe haven't been shown, exploring them and creating an OC there isn't hard to do. Bonus points if they stick to the Theme Naming all these have.
• Fairy Tail:
  • These usually manifest as previously unknown Dragon Slayers, the most popular being of the Water element. Ice and Earth (the element, not the planet) are also somewhat prevalent, along with a couple other, weirder ones, like Crystal or Light.
  • Some people like to create new Celestial Spirits for Lucy (or, rarely, for a fan character) to use. As there are literally dozens of unused constellations to choose from, this leaves open a lot of potential. However, instead of being Silver Keys like all non-Zodiac constellations are supposed to be, these sometimes get hit with super-powerful White Keys or Dark Keys. Common constellations for these super keys include Pegasus, Canis Major (Lucy is seen buying the Canis Minor key in episode 1), and Draco.
• Food Wars!: OCs tend to be either New Transfer Students to Tootsuki like Soma or someone who has "The Devil's Tongue" as a counterpart/Foil to Erina.
• Fullmetal Alchemist:
  • The Sailor Earths usually come in the form of State Alchemists in their teens, proficient in a field of thematic alchemy.
  • Extra homunculi. Never mind that the Seven Deadly Sins motif puts a firm cap on the number; plenty of fanfic writers don't care and just start coming up with their own vices. They were especially common for fanfics based around Fullmetal Alchemist (2003), where the homunculi were more complex characters and their origin story as failed human transmutations was automatically tragic and could tie them in with the canon.
• Fushigi Yuugi easily allows for a new Priestess to appear. And she can be from wherever the author is from, even if it's not Japan, because the book can make its appearance anywhere in the world, at any time. The Universe of the Four Gods has the Priestesses appear cyclicly (and ideally one at a time), although a writer could easily put in a Priestess for her favorite of The Four Gods (and favorite Seishi) out of order, and/or have two or more Priestesses appear at once. (Although, canonically, this will screw up the universe and require someone to come along and recalibrate it. This is almost never explored in most fanfiction, however.)
• Thanks to Gundam's rich history, especially in the Universal Century, it's not impossible for some hotshot rookie who is a Newtype/Cyber Newtype/Gundam Fighter/Coordinator/Innovator/what-have-you pilot some super awesome Gundam to fight the evil forces of Zeon/The Titans/Neo-Zeon/Crossbone Vanguard/Zanscare Empire/OZ/ZAFT/A-Laws/what-have-you. It doesn't help that, in the One Year War-era, we've seen tons of fronts of the Federation/Zeon war.
  • A good rival for this kind of character would be a mysterious man with a Cool Mask who pilots a red Mobile Suit with three times more advanced specs than the standard model. Why not? It's common in canon!
  • And it's really easy to come up with new Mobile Suits. Simply take an existing model (Zaku, Leo, GINN), change its design a little, and you have an instant variation. It's flat out encouraged by the Mobile Suit Variations supplemental material.
  • Doesn't happen as often as you'd think with the fan-favorite Mobile Suit Gundam Wing, since most writers focus on other subjects besides the war with OZ. Interestingly though, Shin Super Robot Wars pulled a variation on this by making the Original Generation mecha R-Gun the Wing Team's Sixth Ranger, even having it be designed by Howard, a canon character who may have had the know-how to make a Gundam but not the inclination.
  • Gundam Build Fighters and Gundam Build Fighters Try makes it just as easy to make a Sailor Earth of sorts, since it's normal people piloting heavily customized models (or not).
  • With the advent of Gundam Build Divers, the sky is officially the limit on both pilots and Mobile Suits. Since the series is set in an MMO with wildly variable player avatar appearance rivaled only by Second Life, a pilot can have any appearance imaginable, from default RPG protagonists like Riku to adorable furries like Rommel or hilarious Araki-style bishonen like Magee. Mobile Suits are also only limited by the imagination, since the show features some extremely unlikely concepts like a Super-Deformed Combining Mecha, or a tiny penguin Meta Mecha. Come up with your avatar appearance, design or redesign an existing Mobile Suit, perhaps come up with a themed Force group (the equivalent of MMO clans/guilds), and you're ready to go.
    • In a series of model designs for Gundam Build Divers Re:RISE, Captain Zeon unveils a companion unit for Kazami's Justice Knight Gundam based off of the Strike Freedom.
• Gunslinger Girl: OCs aren't hard to make. Just have a child with no guardians get transformed into a Cyborg Child Soldier and given a handler. It's known that there's more than one generation of cyborgs, however generation 2 barely appears. Some fanworks feature a male cyborg character.
• Original Haibane are extremely common in Haibane Renmei fics. A few are based on the Babies Ever After ending, however most are simply original characters with Dark And Troubled Pasts who have unusual wings.
• Hetalia: Axis Powers:
  • Since the characters are all Moe Anthropomorphisms of countries, it's very easy to create an OC by selecting any nation that hasn't shown up in canon; you can even opt to make a province like Canada's Quebec or The United States' states into a character. You're expected to do some research to make sure that your OC reasonably fits that nation/province's stereotypes and history, though, and inventing a country out of whole cloth just reeks of lazy writing and/or Self-Insert Fic.
  • Many people liked to put someone in for the missing North Korea, until a blurb on Himaruya's site was finally translated, stating many important details about him.
  • A weird case happens with Latin American countries: Since the only Spanish-speaking countries that appear in the manga and the anime are Spain and Cuba, Latin American fanfic writers love to include Latin American OCs as part of the cast, even if many of those countries didn't have a steady contribution in World War II.
  • Just search "Yakko's World Hetalia" on YouTube to get an idea of just how many of these characters exist.
• Inuyasha:
  • Sailor Earths may be another human, demon, or hanyou who was cursed by Naraku or has another bone to pick with Naraku for some reason. Naraku is Hated by All, so it is only natural everyone has a bone to pick with him.
  • Bandai Entertainment used this for their InuYasha RPG adaptations. Inuyasha: The Secret of the Cursed Mask for PS2 has either a boy or a girl and Secret of the Divine Jewel for NDS has American transfer student Janis, all of whom are Kagome's Expy upon their introductions. While they have their own plots, the whole point is only to have their original characters go on a quest along with the Five-Man Band.
• Jewelpet, thanks to its concept of tiny animals who represent minerals, has an ungodly amount of original characters based on minerals not (yet) used in the franchise.
• JoJo's Bizarre Adventure:
  • Creating new Stand users is simple: pick two musicians, bands, songs or albums, then name the user after one and name the Stand after the other. There was originally a heavy bias for American and British rock from the '80s or earlier, but as time went on '90s references began trickling in, and Part 7 introduces Japanese pop while Part 8 brings in 2010s American pop. The series doesn't even have a strong precedent for relating character or stand names to characterization or abilities, so you've got carte blanche to make whatever random music reference you like.
  • Go to a baby names website, pick "J", and scroll until you find the "Jo" names. Then pick whichever one sounds the best to you. Congratulations, you just found the name of the newest member of the Joestar family, who can be the lead character of your fanfiction! Nor do you automatically have to restrict yourself to just "Jo" names, since two of the canonical JoJos rely on Alternate Character Reading to make the nickname work, and a third has first and last names whose first syllables simply sound similar to "Jo". So any name that contains something similar to "Jo" can work.
  • When Stands were first introduced in Stardust Crusaders, they were named after the major arcana of tarot (with or without an additional word — there's "Star Platinum," but there's also just The World), and later after Egyptian deities once the author had run out of tarot cards (e.g. Bastet). One could potentially use the minor arcana, court cards, or alternate names of the major arcana, and the many leftover Egyptian deities (or any pantheon if you really felt like it). This sometimes even extends outside of these two motifs; Lotería cards, for example, are gaining traction as a Mexican counterpart to the Tarot naming theme, due to many of the cards resembling those from the major arcana.
  • The non-canon Light Novel Jorge Joestar introduces an universe where Stands are named after movies, further expanding the naming possibilities. And now that you're willing to break the rule of music reference names, the floodgates open for naming Stands after just about anything you can think of: people have come up with Stands named after literature, TV shows, and video games.
• For Kamichama Karin, all you need is another Greek god.
• It's becoming a common trend to make Kill la Kill fanfics centered around other students of Honnouji Academy, usually they're either club presidents or one of Satsuki's associates.
• The Kinnikuman fandom and Yudetamago themselves encourages the creation of new Chojin, since most of the Chojin seen within the manga are fanmade creations made official. All you need to do is create a gimmick for your wrestler, their country of origin, their alignment (Justice, Devil, Brutal, Perfect or Time), and some of their signature wrestling techniques, and you're basically set!
• Lyrical Nanoha, from StrikerS on with its Mildly Military setting, allows for the existence of other TSAB teams and units that can act alongside the canon characters.
• My Hero Academia has an extremely fertile setting for OCs, given that it's a world in which 80% of the human population is born with superpowers, ranging from near useless to completely overpowered, to everything in between, and the main cast are the students of resident Superhero School U.A. Academy; said OC will usually join U.A. as a New Transfer Student, and will be placed in Class 1-A, presumably filling the vacant spot Mineta left after the author had him kicked out of U.A. (often because of his perversions).
• Naruto:
  • The hosts of Tailed Beasts 3 and 5-7. The fact that a cover celebrating the manga's 9th anniversary give designs for all of them◊ despite most of them being killed offscreen with little or nothing about them known just encourages this.
  • The Six-Tails host, Utakata, gets his own filler arc in the anime.
  • For that matter, there apparently was no host for the Sanbi by the time we see it; Deidara and Tobi fight and capture the beast itself.
  • There are also the extra tailed beasts people come up with later, e.g. the Ten-Tailed Wolf. Or the people who seal the yin half of the Kyuubi into another host. It was eventually revealed that a Ten-Tailed Beast does exist, but it is actually the original tailed beast, the other nine being fragments of it split apart by the Sage of Six Paths.
  • The fandom also seems to be in the habit of inventing other members of the Seven Swordsmen of the Mist, of which only Kisame, Zabuza, and Chojuro were mentioned. The more intelligent ones preserve the Theme Naming and the odd swords. The less detail-oriented, and the filler writing staff, don't. Too bad all of them eventually showed up in-canon. (Albeit as zombies in most cases.) Though given that the Seven Swordsmen recruit new members to replace those who die or leave the group and Chojuro is the only active member by the time of the final arc, there's plenty of room for replacement members to be invented. And in the epilogue, Chojuro has been promoted to Mizukage, meaning his own slot is presumably open for a successor as well.
  • For that matter, not only are the 5 major villages relatively little-known, but the canon map displays a dozens of tiny countries that could house new minor ninja villages; the filler writers certainly made good use of this.
  • Not that there isn't plenty of Sailor Earth material in Konoha itself. Just have a character be from some second-tier clan with some "(usually a Japanese word)-gan" Kekkei Genkai. Or even make them a long-lost Uchiha or Uzumaki clan member. Or make them a member of one of the other clans that "only" have specialized techniques and not a bloodline ability, like the Nara or Akimichi.
  • Spin-Offspring series Boruto made way for a new type of Sailor Earth: next-generation characters. Like a character and they apparently have no kids yet? Make some for them! Most of the Konoha 12 have at least one child, however that leaves room for characters like Kiba and Tenten who don't. There are also OC siblings for the existing characters (such as Sarada receiving a, usually pink-haired^note Sarada, the daughter of Sasuke and Sakura, inherited Sasuke's black hair, brother or Shikadai gaining a sister).
• Neon Genesis Evangelion: Nth Children, Nth Angels, Nth Evangelion Units, extra bridge bunnies, SEELE agents... It's such a popular plot that even Rebuild of Evangelion and the official Tabletop RPG of the series ("The White Paper", Japan-only) runs with it.
  • Want to make a new angel? There are literally dozens of names in biblical canon that the series doesn't use. Azrael and Samael, the angels of death, are particularly common. Sometimes, fans will opt to just add "-iel" to the end of an English word. Case in point: Clockiel, the fan name for the Seventh Angel in Rebuild. The first Shinkalion crossover episode even shows an Angel that is a fusion of many of the canon Angels.
• Ojamajo Doremi:
  • Sailor Earths often pop up as the green Ojamajo. Similar to the Organization XIII case, a green Ojamajo, Nozomi, actually showed up in the OVAs. The clue? She died from cancer, and was the only character in the series to really die. Ojamajo fancharacters almost invariably show up as green, and named "Fasola," in order to establish some sort of Theme Naming after Doremi. If not green, expect rainbow, or a mix of two or more colors, which will form an alternating pattern on their dress. Bonus points for black and/or red (even though, like Nozomi, there IS a red Ojamajo — Poppu) or if they are somehow related to Onpu.
  • Fairies in the show are named after the notes of the Solfège... except "So" and "Ti". As you might expect, a lot of fanmade fairies have one of those names.
• One Piece:
  • Before Brook joined the crew, the fan-made crewmember was almost always given the job of ship's musician. These characters still pop up in One Piece fics all the time, though; they're simply given a different job, often one that is made up for the fic (such as "helmsman", even though the crew has never expressed the need for one and usually just take turns at the helm ^note though this eventually became Jinbe's position once he officially joined the crew). This likely stems from an early (and possibly outdated) statement by Luffy that he wanted ten crewmembers, and Jesus Burgess' position in the Blackbeard Pirates.
  • Back before all the Warlords of the Sea were revealed, it was common for some OC villains to be this. This was back when Mihawk and Crocodile were the only ones revealed to be one and actually be made as characters, where Doflamingo and Kuma, while revealed, had little screen time. Other popular positions were Admirals and other high-ranking Marines. Since there were two vacancies among the Warlords before the system was abolished entirely and an unknown number of former Warlords, and one Admiral with no information known other than his/her code name, there remains plenty of room for such characters.
  • Original characters with any Devil Fruit the writer can imagine. Just think of a word, come up with powers that relate to it, and come up with a character to use it.
• Overlord is about a player of a futuristic full immersion MMORPG (called a DMMO-RPG) ending up in a fantasy world unrelated to his game, but with the appearance and skills of his in-game avatar. As an MMO "so popular that whenever the word "DMMO-RPG" was mentioned, listeners would immediately think of [it]," the game would doubtlessly have millions of players. Given the only (known) requirement for being transported to the New World is that the player be logged in when the servers were shut down for the last time, any of these potential millions of players could be a new OC.
  • Bonus points for the game's in-universe main selling point being player freedom, allowing people to roleplay as anything from a Knight in Shining Armor or Princess Classic to The Undead or giant crab men.
  • Players were also given the ability to create their own custom Non-Player Characters. In the series, it's shown that these characters could be customized to the same extent as the players themselves, and could be used to defend player-owned areas and for roleplay. In the New World, all these characters come to life and live in accordance with their player-written backstories, providing an entirely different source for an OC. And a way for a player character other than Momonga/Ainz to have their own built-in supporting cast.
• Pokémon:
  • Creating new Trainers to meet Ash is not hard to do, given just how large the world is and how many tournament Trainers are not given personality for a perspective writer to take over as their own.
  • On a similar note it isn't hard to add new Pokémon to a Trainer's roster.
• Powerpuff Girls Z: Fans, naturally, have taken to making their own versions of these alternate Powerpuff Girls. One of the more common attempts is for fans to cook up their own version of Bunny.
• Pretty Cure:
  • As a franchise, any given season of Pretty Cure features a stated theme and characters of various colors to represent it, called "Cure (Name)". Sometimes the theme isn't even strictly adhered to in the show itself, allowing for a lot more flexibility in character naming so long as they're still a "Cure". Hence, it's very easy to stick extra characters into a pre-existing season by picking an unused color from the palette to create a new Cure adapted to that season's lore and theming. Some fans take the idea even further and invent entire "fan seasons" using this format, creating entire teams of Sailor Earths loosely connected to the franchise.
  • Until her identity was actually revealed, there were a reasonable number of fan-created red Cures for Fresh Pretty Cure! based on the fourth petal of the clover logo. Since said clover also had a green center, the idea of a green Cure or Cure-like ally was also popular.
  • HeartCatch Pretty Cure! saw a few yellow and purple Cures (possibly due to the logo featuring yellow and purple in addition to pink and blue)... but only briefly, as Cure Sunshine and Cure Moonlight's appearances were leaked very early on. There is still Sailor Earth potential — in this continuity, there were numerous Cures who had their own adventures long before the main heroines did, though they only appear in-series as anonymous statues. This was even done in-universe! When Potpourri was searching for the third Cure, he encounters Ban, who is trying to come up with a Sailor Earth of his own, Cure Fire, for his manga. When Potpourri suggests he be the third Cure, he starts imagining himself as such. Potpourri runs for the hills and Ban uses Cure Sunshine when she appears.
  • Smile Pretty Cure! features a Transformation Trinket design with seven different-colored lights. Five of them correspond to the main characters. You can see where this is going.
  • HappinessCharge Pretty Cure! toys around with the trope, establishing other teams of Cures fighting the Phantom Empire around the world, thus allowing fans to come up with new Cures without affecting the core team. Cures are so common in this universe that people barely even react to them.
  • HuGtto! Pretty Cure really opened the floodgates by establishing the franchise's first male Cure, Henri, who becomes Cure Infini. Then everyone in Episode 48 transforms into a Cure to help the main team. Anyone can be a Cure indeed!
• It's very easy to make a magical girl for Puella Magi Madoka Magica, what with the billions of girls on earth to be contracted in past, present and future, and the revelation that Kyubey's kind visit other planets as well only made it easier. The only real requirements are they have to have misery in their lives in some way, their soul is now outside of their body, and they will either break or die, depending on how cruel you are.
  • One can even make another Incubator if they wished. Since Puella Magi Kazumi Magica revealed Juubey, people are running with the idea of them being a numbered series. As it turned out, Juubey was a special case, and his name isn't (entirely) a number pun. The theory has been Jossed to some degree, since Word of God and several spin-offs suggest that the species is an emotionless and uniform Hive Mind. However, Kyubey admits that there are members of his species who suffer from a "mental disease," which has prompted the creation of many a Defector from Decadence... or the occasional creature that would be evil even by their standards.
  • If your story is set previous to the end of the series, it is also fairly easy to create your own Witch. There is an infinity of them all across the ages, with an infinity of gimmicks, new ones appearing every day. There's even a template all laid out for you by the official descriptions: a name, a mindscrewy design, a nature and a short description for the witch herself. Another name, design, duty and short description for her minion. Given that "birdcage witch" and "class representative witch" are valid Witch gimmicks (both appear in the anime), then you can see Magical Girls can never run out of enemies to fight.
  • As shown in Puella Magi Madoka Magica The Movie: Rebellion witches can still appear after the end of the anime, but only under special circumstances. Also, they can now be Guardian Entities, or the result of Voluntary Shapeshifting.
  • Thanks to Magia Record and its many playable magical girls, it's now possible to make a magical girl summonable in that series as well. Introducing the concept of Doppels (forms where a magical girl is half-fused with their personal witch) also allows them to come up with what their integrated powers look like.
• Ranma ½: Other victims of the Junsenkyo Springs is a pretty popular plot, as is the concept of other fiancees for Ranma (or a Love Interest for one of the other characters).
• Reborn! (2004) is a story with only the most prominent mafia families in that universe. Also, the Vongola might have quite a lot of enemy families. One can easily whip up their own family with some Italian-like name, and then fill it with many original characters.
  • Actually having more than seven rings and seven colors was sorta canon, as said in one of the games, but there was a specific reason why the topic of an eighth ring isn't touched upon.
  • The Vindice seem to be the only known characters in canon that have access to the eight element, and it seems to be so powerful that Daemon Spade thought that if he had it, he could beat the combined forces of Earth and Sky.
• In the Rozen Maiden anime, there is another dollmaker named Enju, who only made one doll. He is often seen as a plot device with which to bring in more dolls without affecting the Rozen Maiden lineup.
• Sailor Moon:
  • Any hypothetical Sailor Guardian, but especially the obviously missing "Sailor Earth". (This role is technically filled by Usagi's boyfriend and future husband Mamoru Chiba.^note Mamoru/Endymion has the Golden Crystal, the Sailor Crystal of Earth; however the rule is that only women can be Sailor Guardians, so this makes his Tuxedo Mask form the closest to a canonical Sailor Earth.) The manga's creator later admits that none of the later Guardians were actually planned out before they appeared, since the series was initially intended to only feature the few girls to follow the Five-Man Band rule; once the manga's fourth arc made canon the existence of asteroid Guardians with Sailors Ceres, Pallas, Vesta, and Juno, the door was flung wide open. As a result, any astronomical object tends to get a Guardian,^note though it's not likely anyone is going to make a Sailor 99942 Apophis or a Sailor 47 Ursae Majoris b and this was going on well before Pluto was demoted from planetary status. Stars are extremely common targets for fan Guardians, the most prominent continuing to be creating a Sailor Sun (aka Sailor Solaris if you're being technical). Following Pluto's demotion and Ceres's promotion in 2006, Guardians representing the other three dwarf planets, especially Sailor Eris, as well as several of the likely dwarf planets became popular subjects. Not to mention Guardians for planets in our solar system that have been proposed to exist but are generally accepted as fictitious, like Planet X/Nemesis (the supposed tenth planet, which is canonically home to the Black Moon Clan) or Vulcan (Mercury's supposed twin on the other side of the sun). Guardians representing the solar system's other moons are also reasonably popular thanks to the title character, especially since the anime implies that the Sailor Starlights are also lunar Guardians. Authors familiar with other space-centered series could even have one of their characters become a Sailor Guardian using a planet name from the other fandom (such as a 'Sailor Eden').
  • Although the Guardians' uniforms are shown to be vastly different around the galaxy, with the Sailor collar being the only component that's always present (compare the Starlights and the Solar System Guardians), many OC creators tend to stick with the Sol Guardian uniform; it's probably because it's the easiest to work with, having the most examples and being fairly consistent. And if Fan Works involve making a Sailor Earth possible, many find themselves pressed for creative ways to take Mamoru and his alter ego Tuxedo Mask out of commission so his Sailor Crystal can be passed to someone else; some others simply make her his sister and/or have their character embody a different aspect of Earth than what Mamoru does.
  • As far as canon-character candidates for Sailor Earth go, Naru is the most popular; a long-standing rumour is that Naoko Takeuchi would've had her become Sailor Earth if the need for a character with that title arose.^note At least in the Western fandom; Japanese fans back in the day theorized that Naru would actually become Sailor Saturn.
  • An early appearance by a Sailor Pluto in the second story arc fueled the early speculation there should be guardians for Saturn, Uranus, and Neptune. Fanon versions of these guardians existed before canon versions, who were not introduced until the third arc. In the infamous Toon Makers’ Sailor Moon that only had the first arc to go on, the absence of Saturn, Uranus, Neptune, and Pluto would have been a plot point.
  • It also lends itself to crossover fanfiction well, either with original characters or reworking a character from another franchise, usually sci-fi and picking a planet or even just a country or area from the other franchise's lore. This approach grants you a Sailor Gallifrey, Sailor Naboo, or Sailor Arrakis.
  • This trope also applies to villains, as the series employed largely gem- or mineral-based theme names to each villain group, with a slight tweak for themes. Thus, most fanfic villain groups find themselves named after whatever collection of gems or minerals the author thinks is menacing enough. Double points if that gem or mineral ends with "-ite" (common examples being "Quartzite" or "Pyrite") and triple points if they're a missing King (often mislabeled "General") from the first series.
• In Saint Seiya, it's very common to find new Bronze or Silver Saints, since not all the 88 constellations are shown to have an assigned Saint in canon (and often the new saint OCs are based on other mythical creatures or beings) and it makes it fertile ground for fanfic writers to introduce their own saint OCs, the same could apply to Hades' Spectres or basically the army of any god.
• In Sekirei, only about half of the canonically established 108 Sekirei have been introduced or given names. Plenty of room for fans to make new Sekirei.
• Soul Eater takes place in an Extranormal Institute and only focuses on three students at that school, leaving the rest of the students open to any fanfic writer's desires.
  • Seven if you count the weapons (who do indeed have to attend classes and take exams). Given that there are only six other students (three meisters and three weapons) who have even minor plot relevance, and barely more than that are so much as given names, an author could easily add dozens of OCs without the slightest contradiction of canon.
• Tokyo Mew Mew makes this easy; there's an almost infinite amount of sweet foods and a lot of endangered animals.
• World Trigger, due to the nature of Border being a fairly lax military organization based around kids and teens who fight evil with little to no fear of actual injury or death. Though many members of Border are trainees, the main fighting force is the B-Ranks, which is said to consist of around 100 people. The fact that only 30 out of these 100 have actually been named and introduced so far leaves plenty of room for fans to create their own squads within Border, each with named members, roles, and unique Trigger sets. One can also easily slip a new character into the canon by having them move to Mikado City and join Border as a trainee, since it's really just that easy (as long as you have the Trion).
  • The series later establishes the seemingly endless sea that is the Neighborhood, and the different "planet nations" within it. Aftokrator in particular is said to be split amongst four major houses, which also have minor houses, and lesser houses beneath that! An OC can easily be introduced as a horned Neighbor existing within these houses, possibly with one of the many Black Triggers that the country is said to hold.
• Yu-Gi-Oh!:
  • You could add character around a certain strategy (e.g. Milling).
  • Another common fandom trend is an eighth Millennium Item, though usually the details of how it was made aren't explained. Some authors give this eighth item to Yugi's group, usually Anzu/Tea; one such fanfic sees this item serve as Tea's equivalent of Atem switching places with Yugi via the Puzzle (Tea's alias was given the name Kaylian Paris).
  • A lot of RPs take place in a Yu-Gi-Oh! GX era, where your character can simply be a student at the dueling academy.
  • Yu-Gi-Oh! 5Ds has the Signer Dragons. With Leo becoming the Sixth Signer, despite the show originally only having 5, this led to people making their own Signers and Signer Dragons.
  • Yu-Gi-Oh! ZEXAL fanfics often introduce Number Hunters, or people who hold Numbers, or new Barians. Though all of the base Numbers have since been revealed, alternative Number monsters such as Chaos Numbers and Barian Numbers do still leave some wiggle room.
  • The many factions of Yu-Gi-Oh! ARC-V give people opportunities to introduce a new student to any of the dueling schools, or a character from another summoning faction. In particular, the lack of a canon Ritual Dimension opens up a lot of possibilities for fanon creations. Some even go as far as introduce a third character (often a girl) with a set of dimensional counterparts, despite the plot not having even explained yet why there are already two.
• Though rare, YuYu Hakusho fanfics may involve a future spirit detective (since it is not stated whether or not Yusuke was succeeded by another teenager), another participant in the Dark Tournament or king's tournament, another student who wasn't taken by Dr. Ichigaki, a past student of Genkai, or someone from Mushyori city who became spiritually aware when the demon gate was opened (since Genkai stated that there were a lot more people who came to her after developing powers than just Kaito, Yana, and Kido).
• Zatch Bell! is a favorite with this trope because it allows for double Sailor Earth. Since most of the demon children on the run for Demon King were never introduced, it's no wonder fans write in their own Demons and Book Masters in periods were it was possible. Others go as far as writing about another competition 20 Minutes into the Future despite the main character's motivation being ending said competition.
  • In their defense, the manga ending has Zatch winning and becoming King. In a letter to Kiyo in the epilogue, he reflects on the competition (called the God Trial) and noting the competition as an important and necessary thing. It was through this that many characters (Demons/Mamodos and Humans alike) underwent Character Development, learned valuable lessons and grew to be better individuals, and the way Zatch words it implies that not only have the others realized this, this was the whole intent of the competition in the first place.
• Zoids, in the New Century and Fuzors series at least, involves an entire league of teams battling for fun, profit and prestige. How many fanfics have started with the main characters battling a new team? The same could be said of nearly any other competitive sports show out there; Beyblade, Crush Gear Turbo, Battle B-Daman...