Depending on the board, Avatar: The Last Airbender fandom is either surprisingly civil or at least as bad as any other. The main fight is between Kataang (Katara/Aang) and Zutara (Zuko/Katara) (and yes, there are Portmanteau Couple Names for all of them). Watch out for Ship Mates. Overall, the series makes a very good example of the dynamics of most ship-to-ship warfare, as Katara/Aang had almost all of their interests in common and would arguably have been the more healthy (and slightly more realistic) relationship while Zuko/Katara had complementary personalities ("chemistry," although that could also refer to how entertaining the two characters were together on screen) largely driven by complementary psychological issues (he has mommy-abandonment issues, she has a maternal complex) and were much more entertaining together, thereby turning the whole thing into a grand debate on how relationships work and what the purpose of fictional relationships is.
The series finale features literal Ship To Ship Combat, in addition to ungodly amounts of Ship Tease. Given the creators' awareness of their fanbase's tendencies and the ship-tease short they put together for Comic-Con, the odds of this being unintentional are approximately zero.
The was also the whole Mai/Zuko (shared interests and overall philosophies on life, very little chemistry) versus Zuko/Katara (no shared interests and totally opposed philosophies, but very charismatic) spiel. The battle seems to have died down a bit, but there are still many fanatics who subject Katara or Mai to Die for Our Ship. Mostly Mai, as thesevids demonstrate. Good luck finding similar vids bashing Katara. The situation heated up even more when Bryke confirmed that Aang and Katara have a kid when they announced The Legend of Korra, with some Zutarians even insisting that Katara had to have gone to Zuko for comfort after Aang's death (if not well before). The latter has some Zutarans heralding the "revival" of Zutara, or claiming Zutara to be an Anchored Ship.
Although never very serious, Aang's limitless entertainment-chemistry with Toph has produced a camp that holds that those two belong together, realism and health of such a relationship be damned. Other shippers treat the suggestion as a joke, which it usually is.
Some people even claim Lin Beifong was Aang and Toph's daughter (due to the fact that Aang has suspiciously been Lin's favorite person), not taking into account the fact that that would make Lin Beifong and Tenzin half-siblings who dated. The same with people who claim Sokka was Lin's father, making Lin and Tenzin cousins.
Zutara was taken to another extreme when Zuko was revealed to have a daughter who became the next Fire Lady, but her mother was not named, causing Zutarans to go so far as to claim that Zuko's daughter was his and Katara's, even though Zuko most likely married Mai, and Katara married Aang.
What's worse is that the established relationship of Zuko and Mai at the end of the series has been broken up in the spin-off The Promise. Since Zuko does have a canon grandson he does or did have a relationship with someone. The resulting fan war could tear the very internet apart. Ironically, Katara is probably the only female that is not single by the end of the comic.
In both The Promise and its immediate sequel The Search, there is also a subtle tease at Zuko/Suki. Sokka/Suki and Maiko fans immediately applied their war-paint, but it looks like this shipping war is going to be a long one. As opposed to Zuko and Mai, Sokka and Suki are very much still on; so far, Suki's feelings for Zuko can also be interpreted as a healthy concern for a dear, troubled friend. The third installment will not involve Zuko at all, meaning Suki probably won't be seen very much either, so the true battle has yet to fully begin. Rest assured, it will probably be epic.
Ever since the finale has aired, Mako is starting to get shipping-related hate for an entirely different reason: he and Korra hook up, which is all fine and dandy...but we aren't told if he officially broke up with Asami beforehand. It's certainly feasible that they ended things offscreen, but now you have people claiming he's most likely two-timing both women. Ironically, at the end of Book Two... Makorra has been sunk too, with both of them aknowledging they're Better as Friends.
Ever since the revelation that Lin and Tenzin once were in a Childhood Friend Romance, the Tenzin/Lin shippers have started to push for their ship and bash the shit out of Tenzin's actual wife Pema, labelling her as a slutty homewrecker without any evidence. Naturally, the Tenzin/Pema fans have retaliated...
Cyborg was completely left out of this. Apparently shippers either liked him too much or hated him too much to ship him. We may never know.
Actually, there was a quick Cyborg/Raven vs. Cyborg/Jinx ship battle, but it didn't last long, as most accepted that he's best paired with Bumblebee.
Parodied in the show itself; Control Freak is broadcasting a live feed of his Death Course to fellow geeky supervillains, and they briefly argue about whether Robin or Beast Boy is better for Starfire.
Oh, be thankful that the shipping wars of Daria are over! There are STILL Daria/Trent shippers out there — the biggest contingent, who were set to declare holy war when the Word of GodJossed that pairing in the third season finale by showing that reality would never support the pairing. Still, that's NOTHING compared to what happened a season later. Want to start a war in Daria fandom? Two words: "The Kiss." Daria/Tom shipping has caused heated arguments the way the Sun provides heat and light for the Earth. And the real irony is that in the end of the show, they broke up and Daria stayed single, so neither pairing is is One True Pairing.
Then don't forget those who still cling desperately to Daria/Jane.
Where to start with the convoluted Ben 10 fandom? Said fandom has three major ships, Gwen/Kevin, Ben/Gwen and Ben/Kevin. During the air of the original series, the Ben/Gwen and Ben/Kevin shippers were the most common (Gwen/Kevin was still a Crack Pairing)...
There seems to be attempted Ship Sinking in Season 2, what with the added emphasis on Ben's Canon girlfriend Julie. The primary effect of this has been to make Ben/Gwen shippers and Ben/Kevin shippers ally against their common foe.
The Code Lyoko fandom features a large group of people who ship Aelita and Odd and are combated vigorously by the people who support Aelita and Jeremie, the show's Official Couple. But of course this is nothing when it comes to the Ulrich/Yumi/William/Sissi debates.
As this fanart will demonstrate, not even Thomas the Tank Engine fandom is safe from shipping wars. It does not help however that that some of the episodes have hinted towards crushes between the engines (such as Rosie trying to follow Thomas everywhere in her introductory episode, or Thomas blushing on seeing Flora in her introductory episode). Brain Bleach is on offer here.◊
The Kim Possible fans of the Kim/Ron pairing will viciously attack any fans of Kim/Shego like a piranha-feeding frenzy. Any sign of Kigo Fan-Art will invariably get several negative comments from a Kim/Ron supporter; the same can be said of any Fan Fiction.
And of course, Kigo shippers will invariably call the Kim/Ron pairing "mainstream" or "not gritty enough" or accuse the Kim/Ron shippers of homophobia.
The Chip 'n Dale Rescue Rangers Ship-To-Ship Combat is actually about only one pairing, namely Chip/Gadget. Those who favor that pairing oppose those who do not want to see Chip and Gadget together, regardless of alternatives. This led to two flame wars on the Usenet in 1997 and at the fan forum Acorn Cafe in 1998. Further flame wars could only be prevented by the experience gained during 1998's St. Valentine's Day Massacre and by "agreeing to disagree". A third, rather small faction among them call themselves the Neutrals and dislike the wary ways of both Pro and Anti fundamentalists. Mind you that there has never been a canonical pairing in this show.
South Park has a lot of this, especially since You're Getting Old aired, where Kyle didn't want to be Stan's friend anymore, and was seen playing with Cartman and smiling at him at the end of the episode, implying that the whole Foe Yay between Cartman and Kyle is slowly replaced with a building friendship. The rabid Stan/Kyle and Cartman/Kyle fans went crazy, especially since there was a war between the ships even before the episode.
Then there are smaller battles in the fandom, between Cartman/Butters fans and Kenny/Butters fans, Cartman/Wendy vs. Stan/Wendy and Craig/Tweek vs. Craig/Thomas vs. Craig/Clyde.
As of season sixteen, especially on sites like Tumblr, Stan/Kyle fangirls have begun whittling down or switching in favor of Cartman/Kyle, which in Cartman Finds Love becomes somewhatcanon. Yet, this only escalated the fighting even more, and fans of other pairings like K2 and Candy have also jumped on the bandwagon of standing their ground against the growing number of Kyman fans.
Season 17's run continued the fight between Stan/Kyle fans and Cartman/Kyle fans, with some proponents of the latter hoping it would be officially canonized. Come "Ginger Cow", where the entire episode involved Kyle being humiliated by Cartman and made to "eat farts". This was either seen as deconstructing and shining a light on how unhealthy Kyle would be with Cartman- or alternatively, used by specific Kyman fans as FURTHER proof and fodder for the pairing, with them trashing Stan/Kyle in the process.
Gwen / Trent, also originally canon, used to be heavily involved in this fray too before being sunk. They still tend to side with Duncan/Courtney as a Ship Mate, though, as do Cody / Gwen supporters.
Loony Fan Sierra, Cody's Stalker with a Crush, is the perfect casus belli of Shipping Wars. Many Noah/Cody and Cody/Gwen supporters despise her, though the more forgiving ones are willing to tolerate her after season three ends with her and Cody as Just Friends (and the resulting fact that she no longer makes his life a living hell).
And there is the well known, Flippy/Flaky vs. a part of the fandom that can't stand the couple.
The Invader Zim fandom has little fighting, probably because the show only focuses on a few main characters and Dib/Gaz is unpopular for obvious reasons. The biggest ship war is actually just between those who like ZADR and those who despise it, especially since Jhonen Vasquezsays it makes him "sick to his ill-prone belly." Building on that, there is a small collection of anti-shippers who are against pairings in general, but ZADR is where they direct most of their ire.
There is actually a pretty big fight between Zim/Dib shippers and Zim/Gaz shippers.
In Phineas and Ferb the biggest question is with whom Isabella should end up with. Fans usually ship her with the two principal brothers. That's because she's the only one female character of their age with a important role.
a joke in "Quantum Boogaloo" Ship Teased Ferb/Isabella (Ferbella), but this pair was never developed in the series.
Isabella has a crush on Phineas. Because of this, Phineas/Isabella (Phinbella) simply has much more canon evidence and a significantly larger fanbase.
And now Vannesa broke up with Johnny...but got a thing for Monty Monogram. here we go...
This was mostly averted between Jeremy/Candace and Candace/Stacy shippers. Most of the later also support the former. And there isn't any reported sighting on any debate between the two thus far.
Metalocalypse, despite its veritable buffet of pairings and a fandom that just loves the Ho Yay, has thus far avoided this. Every possible pairing has its supporters, some quite staunch, but as a whole the fandom is laid back enough to live and let live, with the Skwisgaar/Toki, Toki/Nathan, and Nathan/Charles supporters sharing forums and communities in relative harmony.
While not as extreme as some of the others mentioned on this page, there's the Green Lantern/Hawkgirl shippers vs. the Green Lantern/Vixen shippers for Justice League Unlimited, even though both are canon, and there was a big reveal about Warhawk being Green Lantern and Hawkgirl's son in the future, and Word of God has pretty much said the Green Lantern/Hawkgirl shippers have reason to be victorious in this fight. And yet there's still friction between them.
The "Shipping Wars" within the Danny Phantom fandom. It became (in)famously known as the "True-Fan VS Anti-Fan" wars, and ran rampant throughout sites like deviantART. The wars pretty much boil down to Canon (Danny/Sam) VS Fanon (Danny/Valerie) and/or Heterosexual Parings (Danny/Sam, Danny/Valerie) VS Slash (Danny/Vlad, Danny/Dash, and even Danny/Himself *Don't ask*).
How bad was it, you ask? Well, anyone who supported "Fanon" parings was considered an "Anti-Fan" whom the "True-Fans" disregarded as "filth and pornography" (Even if artwork/fanfic of said "Fanon" pairing was completely "G" rated). Likewise, the supporters of "Canon" pairings were called "Canon Nazis" whom the "Anti-Fans" would often accuse of "not understanding artistic freedom". Not to mention that simply being friends or liking the artwork of someone on one side of the battlefield automatically made you enemies with the other. Thankfully, these days, the war seems to have died down a bit.
Wolf O'Donnell stepped forward and created the iconic ship to end all ships. Cream Soup. Other wise known as Danny and the Fenton Thermos. The Cream Soup ship was for those who simply don't want to get so involved in shipping. Fanons are slowly starting to use this one.
The Fairly Oddparents has its own, with the main combatants seeming to be Timmy/Tootie and Timmy/Trixie. However, Veronica/Timmy also has its own devoted fanbase (even though Veronica was only shown to like Timmy in two episodes and she expressed it in a very... interesting way. There is also a minority of Timmy/Vicky shippers, who seem to be in it mostly for the 'straight shota'.
The Tootie/Timmy shippers won out in the end, as the Fairly Odd Movie reveals that Timmy gives up his fairies for Tootie, but a loophole in the rules allows him to keep his fairies, so long as he uses them for unselfish purposes. Tootie also is allowed to learn of the fairies. Although the movie is not the finale of the series itself, it seems to set the events of the future in stone. Despite this word coming from the creator himself, fans against this couple are still trying to claim it is not part of the canon series. Yeah, you heard that right, Negative Continuity Nicktoons have non-canon and alternate timelines now.
Codename: Kids Next Door. Say one shipping, and you'll have shippers SWARMING YOU WITH FURY. For example - 4/86 - You'll have 2/86 after you and 4/3 after you, and 2/86 will have 2/5 after them, which will have 1/5 after them, and will have 1/Lizzie AND 1/362 after them, and so on and so forth. You may want to wear battle ready armor for this.
Gargoyles fandom has had this going on for over a decade after Goliath's daughter Angela hooked up with Broadway over Brooklyn (and Brooklyn himself was very graceful about his "loss"). While most fans understood that Broadway was the correct choice, even if not the obvious choice, there are still fans who believe she should have hooked up with Brooklyn, and it intensified after Greg Weisman came out and said that Brooklyn's attraction to her was shallow and superficial. The arrival of Brooklyn's true love, Katana, seems to have finally laid this to rest... however there are still some hold outs because "Katana is not hot." (This is what Katana looks like, by the way.)
For a period, several years back, there were militant shippers who believed that Demona and Elisa Maza should be a couple. While some were doing it just for the fun, there was a rising faction who was dead serious about it. They even denounced Greg Weisman as a writer, and attacked him for not writing "realistic relationships." So, according to these people, Demona and Elisa were meant for each other. One is a human, and one wants to commit mass genocide upon humanity, and both despise the other.
X-Men: Evolution has a few interesting ones. Lancitty(Lance/Kitty) vs. Kurtty(Kurt/Kitty) is the biggest one and dates back to the start of the fandom. Some Kurtty fans like to bash Lance as a violent bad boy who is all wrong for the innocent and sweet Kitty and should be with someone like Wanda or Tabitha, while Dogged Nice Guy Kurt is the one for her (Sometimes depicting him alot more violently than usual and being rather immature about it). Lancitty fans will point out that Kitty is attracted to Lance, and never showed the slightest romantic interest in Kurt. who is in a relationship with Amanda (Sometimes agressively saying 'ITS NEVER GOING TO HAPPEN' and be rather immature about the matter as well). They are also quick to remind anyone they have canon behind them as the Official Couple since Lance and Kitty are hinted to get back together at the end.
And, that's not even mentioning the Piotr/Kitty fans. Usually, they're spared by the other fans due to Piotr's little screentime, but due to the fact he's Kitty's comic love interest and in a few scenes at the end of the third season Kitty and him proved to work well together he's just as much up for grabs by the less tollerable fans. Sometimes, he'll get off light with just a casual 'It didn't happen', sometimes he'll get a 'he was too old for her' (Which is funny, since his age wasn't ever stated, but he appeared to be only around Scott's age, the same as Lance), but, sometimes he'll just get treated like garbage, or Out of Character Moments from the comics will be given as 'evidense' to him being wrong for Kitty.
Another one is Scogue(Scott/Rogue) vs. Romy(Gambit/Rogue). Rogue had a crush on Scott that last for three seasons of the show; this pairing proved very popular, much more so than Scott's always inevitable hookup with Jean. But it was challenged when Rogue's longtime comic boyfriend Gambit appeared on the show. Now, every detail about Scogue is bashed (Including its name, seriously, some cite that 'Scogue or Rott sounds terrible') by the Romy fans.
And, lets not forget how Jott (Scott/Jean) is treated by Scogue fans. Or Jean herself, who apparently is a slutty evil Alpha Bitch in the view of eabid Scogue fans who think Popular Is Dumb despite how Jean was portrayed sympathetically in the show, or creepily overproject their own teenage experiences on the Love Triangle: Rogue the Misfit is automatically good, Jean the Spoiled Sweet is automatically bad, Scott is Rogue's "prize penis" for being the Cool Girl, etc.
Finn dates Princess Bubblegum in her age-regressed state but it doesn't last. In the episode "Too Young," PB returns to her proper age to evict a "friendly" usurper.
In the episode "What Was Missing," Bubbline (Marceline/Bubblegum) took off big time. The episode itself seems loaded by the writers with slashy tinder.
Finn has a new love interest in the Flame Princess. Shippers are already starting to get into combat mode, with both Finn/Bubblegum and Finn/Marceline shippers screaming at her while Bubblegum/Marceline fans team up with Finn/Flame Princess shippers so they can have their cake and eat it whole.
Finn/Flame Princess is sunk, seeing as how Finn manipulated her into fighting Ice King. She says they can still be friends though.
Despite a little bit of shiptease and a growing number of fanarts, Finn/LSP has mostly avoiding going to war.
Gravity Falls:Just like the Invader Zim fanbase, the biggest shipping war is between those who ship Pinecest (Dipper/Mabel) and those who despise it. The fact that the creator based the two main characters off of him and his sister doesn't help the pinecest shippers at all.
My Little Pony: Friendship Is Magic: There are ships that pair Rainbow Dash with Applejack, but there are others that pair her with Pinkie Pie. Fans of one ship will immediatly (upon realization) state they don't like the shipping, while stating however, that the story is [X] ([X] being their humble, critical opinion on the author's writing) and so living on to their promise of "loving and tolerating the $#¡+ out of you".
While many fans promote "love and tolerance", many still start ship wars, PinkieDashers in particular.
If you pair Lyra or Bon Bon with anypony other than each other, you can expect to at least a few times be called either A) a troll, B) a homophobe, C) an idiot, or D) all three. Many LyraBon fans are perfectly normal, but a lot of them are so possessive of both characters that if you don't accept the shipping of them as "almost canon," you'll soon meet a lot of people who neither love or tolerate your opinion.
And a lot of people found the episode a Crowning Moment of Funny because in a way it said "shipping is bad" since the plot was about making two people fall in love because you think they'll work. Cue a bunch of teasing fanart all around.
Speaking of which, there can also be quite a bit of friction between FlutterMac (Fluttershy/Big Mac) and TwiMac (Twilight/Big Mac) fans (though it doesn't usually reach the fevered level of some of the other ship wars).
Let's face it, you really can't bring up a pairing without people complaining about how that pairing sucks. Notable examples include shipping OCs with canon characters, merely mentioning Trixie in a non-Twilight/Trixie story (because Twixie has quite a few vocal fans), the very implication of Bic Macintosh going with anypony except Fluttershy or Cheerilee, any of the Background Six getting together with anypony other than their double (Derpy and the Doctor, Lyra and Bon Bon, and Vinyl Scratch and Octavia), and most anything involving Princess Celestia.
Based upon recent forums, a three-way conflict seems to be underway. All three factions are fighting over whom Rainbow Dash should be shipped with. AppleDash (Applejack X Rainbow Dash) is the most popular and generally most organized faction; FlutterDash (Fluttershy X Rainbow Dash) seems to have the most zealous and passionate fans; and TwiDash (Twilight x Rainbow Dash), based on the sheer popularity on FimFiction.net, is gaining momentum the fastest out of the three and is recruiting more and more casual first time shippers.
Recently, discoveries have been made that a lot of hardcore shippers of various mane six ships will express notable distaste for other main characters. Incidentally, these characters happen to make up halves of other very popular ships. Examples include AppleDash shippers, who generally hate RariJack and don't take kindly to Rarity, and TwiDash shippers, who often loathe Apple Dash and are quick to dismiss Applejack as a background character, boring, a mudpony, or all the above.
There is also an escalating debate based on who the Wonderbolt, Soarin should be paired with. Soarindash (Soarin X Rainbow Dash) has one of the largest followings amongst the shipping fandom (not to mention an exceptionally high deviantART membership), but faces some competition from Soarinjack (Soarin X Applejack) shippers and Soarinfire (Soarin X Spitfire) shippers as well.
Any shipping involving Discord is subject to controversy. However, following a brief scene in the 4th season's finale in which Discord gives Princess Celestia a bouquet of flowers, a rather heated conflict has emerged between those who ship the two together, and those who ship him with Fluttershy. And that's not even accounting for the debate between "Dislestians", and fans that believe that the relationship between Celestia and The King Sombra of the parallel universe should be taken as canon.
In-universe example: Gargamel starts one of these in the Season 1 episode of The Smurfs "Romeo and Smurfette" when he has a Mind Controlled Smurfette say that she's decided to marry either Hefty or Handy. All the other smurfs take sides, and things get so violent that Papa Smurf has to divide the village with a This-Is-My-Side line to keep Team Hefty and Team Handy from killing each other. We couldn't make this stuff up.
In the Young Justice fandom there are many ship wars, but the main ship war being Spitfire (ArtemisXWally) and Traught (ArtemisXRobin). BirdFlash (WallyXRobin), Chalant (RobinXZatanna), and BabsXRobin often get caught in the crossfire. Some people have compromised with an OT 3, Museum Heist (RobinXWallyXArtemis), which occasionally expands into four with Babs or Zatanna.
Hey now, let's not forget Blue Pulse (BlueBeetleXImpulse).
The show also has some very disturbing pairings being supported. Count Dooku/Ahsoka is what we're talking about here.
Is it any wonder that all of these pairings have Ahsoka in them?
Superjail!: For a time on sites like deviantART, shipwars could get very vicious, especially if they involved male/female pairings vs. male/male ones (or in rarity, female/female). This would lead to some fans from either camp flinging stereotypes about the opposing one, with shippers of heterosexual pairings being called homophobes, and the shippers of homosexual pairings being accused of "oppressing het". Not as bad as Danny Phantom in the end, but still mind-boggling.
In the days of season 1, Warden/Mistress ("Misden"), Warden/Jared ("Jayden"), and Warden/Future Warden ("Wardencest"/"Timeshipping") went head-to-head, with Warden/Jailbot ("Warbot") also another option considered. Once Lord Stingray entered the picture in season 2, select fans of "Stingden" and Misden began arguing over which pairing would be more canon and which of Warden's nemesises was more worthy of him. This lead to both Mistress and Stingray getting hate from the other's fans out of the idea that either one was in the way of their desired pairing. This seemed to die down a little after "Stingstress" since the Mistress wound up sleeping with Alice.
A vocal minority of Warden/Mistress fans have also thrown potshots at Alice and those who ship her with either the Mistress (who they believe only Warden is entitled to) or the Warden (who only the Mistress is apparently entitled to). This was spurred on by the above episode.
While the Warden/Jared vs. Jared/Charise disputes are less frequent or as overplayed as the above, it doesn't make Charise completely immune from being subjected to this and Die for Our Ship by fans who insist that she's "in the way", secretly evil, or not as significant to Jared as the Warden would be. In turn, some Jared/Charise fans even jumped ship to the other pairing after season 3, feeling it'd be less likely for Jared to actually get together with her.
In the least frequent but most baffling example of the trope, some fans go to war over whether the Twins are incestuous or whether they're more deserving of being paired off with women (sometimes even just pairing them off as an attempt to dissuade the Twincest). Seeing as there are very few female characters in the show, it leads to pairings that would be ridiculous anyway, such as pairing one Twin off with Alice or the Mistress.
The All Grown Up! fandom was prone to this and the show's main forum was rife with it. Essentially, it was Tommy/Kimi vs. everyone else, as Tommy/Kimi broke up two of the show's other popular ships (Tommy/Lil and Phil/Kimi). Chuckie/Angelica shippers tended to be more prone toward the Tommy/Lil-Phil/Kimi side of the fence, just to stir the pot further.
An attempt at a fan-written continuation of the series collapsed into a several-page argument between Tommy/Kimi, Phil/Kimi and no shipping at all. This was largely due to long-standing rivalry between the writers involved, but the passion of the whole thing was indeed kind of frightening.
Teenage Mutant Ninja Turtles (2012) has a large one going on. A lot of fans are supportive of Apritello, but the Official Couple is Capril. The large amount of Apritello fans may be a result of the first season not having Casey. Now that he's a part of the show, fans aren't happy and are willing to defend their fandom.