The X-Men franchise is perhaps the worst offender for Superman Stays Out of Gotham.
- Non-mutant heroes with superpowers function side-by-side among mutant superheroes who face discrimination from humans who fear them because they have superpowers. The anti-mutant regulations include high-profile government-sponsored elements such as Mutant Registration Acts and mutant-hunting Sentinels, which the rest of the heroes are well aware of, as The Avengers were once forced to fire their mutant members as a result of increasing public scrutiny (naturally, the Avengers went along with it passively, despite having other members who are just as feared, if not even more feared than the mutants, such as the Hulk) and used a fleet of Sentinels in a major battle against Kang the Conqueror. Despite not being anti-mutant racists themselves, all the heroes who got their powers through other means (and for unexplained reasons are therefore exempted from the Fantastic Racism and government scrutiny) have “somehow” decided the plight of mutants is not their problem.
- X-Men works both ways too. When evil pro-mutant forces like Magneto threaten the world, it's the job of mutants like the X-Men, and specific anti-mutant forces to stop him. Magneto rarely ever has The Mighty Thor or Doctor Strange coming down on him, unless he's done something specific to drag them into the story (beside his usual Kill All Humans spiel). Conversely, the X-Men almost never bother to intervene with any non-mutant villains like Kang the Conqueror or Doctor Doom, even if said villain's latest plot should be causing shrapnel to rain down on the Xavier Mansion's front lawn.
- Wolverine is a perfect symbol of how ridiculous this whole thing can get. He is both a frequent member of the X-Men and an Avenger, often at the same time, meaning one man can be simultaneously part of a persecuted minority and member of a group which is "feared and hated" by the government and general public alike; and also part of a team of beloved celebrities with ties to the US government.
- There have been two storylines of Captain Britain that have an insane reality-warping mutant (one of whom was the superhero's older brother). Even though years back they faced off against Proteus who caused similar havoc in Muir Island, Moira MacTaggert doesn't think to contact them of something taking place in Britain. With the former situation, one gets the impression that Merlyn set the whole thing up in a way that only Captain Britain was supposed to deal with them. Interestingly enough, The Fall Of The Mutants event was supposed to rectify this, but didn't. At least not directly - Excalibur was formed sometime afterwards, with two X-Men (Nightcrawler and Shadowcat) in the team.
- The Civil War storyline mended the hypocrisy, subjecting all superheroes to a Super Human Registration Act. In a twist, the X-Men declared the whole thing not their problem (specifically citing how the non-mutants never bothered to interfere with Mutant Registration Act(s)).
- Similarly, other large-scale threats to mutantkind exist in the X-Books alone. The Legacy Virus was meant to stay active until they found a cure for AIDS but it became a Plot Tumor when the writers had no clear answer for why scientific geniuses like Reed Richards or Hank Pym couldn't find a cure.
- Beast reaches out to nine of Marvel's Mad Scientist supervillains for help in solving the "Decimation" that Brought Down to Normal most of Earth's mutants. They all just laugh in his face.
- A trend that comes and goes Depending on the Writer, and one that at present has "come", is that Marvel's superheroes will act like jerkasses in X-Men comics and the X-Men will act like jerkasses in other Marvel comics, yet they will never be portrayed as jerkasses (or that jerkish, anyway) in their own stories. Witness Reed Richards getting pissed at the X-Men for summoning the giant metal bullet that trapped Kitty Pride back from space (long story), basically a long overdue rescue attempt aimed at saving a member of their extended family, albeit with some (averted) danger to the Earth. Never mind that Reed himself would go to equally insane lengths to save one of his friends or family, that he frequently messes about with stuff that potentially puts the Earth in far greater danger (sometimes for his own curiosity), or that he didn't even give Cyclops the chance to explain that it wasn't even them doing it (Magneto had decided he owed them a favor).
- When Magneto took over New York during Grant Morrison's run on New X-Men he explained that he had tricked the Avengers and the Fantastic Four into leaving on a wild goose chase. That does not explain why none of New York's other heroes who weren't associated with any of those groups did not try to help the X-Men. While Magneto may be a few power levels above them, there is no way Spider-Man, Daredevil or Luke Cage would have stood by and watched while Magneto sent New Yorkers into gas chambers.
- One story did its best to explain why Magneto is usually the X-Men's problem. Immediately after the Legacy Virus is cured, Magneto sets about gathering mutants from all over the world and organizes them into an army on Genosha in preparation for his latest attack on the rest of the world. Questioned by news reporters on why the Avengers haven't moved in to stop him, Captain America explains that, because the Avengers are a government-sponsored team and Magneto is legally recognized as the ruler of Genosha, they can't move in until he actually does something (of course, he subsequently attacked Professor X in his home, kidnapped him and put him on display in the centre of his city, which seems like the kind of thing the Avengers would respond to). At the same time, Israel's main superhero (Sabra, who, like Magneto, is a Mutant as well as Jewish) says that she would be willing to strike him preemptively.
- In the non-canon Universe X comic, one character hypothesises that the more powerful evil forces in the Marvel Universe- for instance, Hell Lords like Mephisto, and other demons and dark gods- actually go out of their way to manipulate characters and events to sabotage human-mutant relations, with the explicit aim of stopping them banding together more often and kicking their collective asses or making the world a better place. This is quite a clever justification, even if it wouldn't explain everything (as demons can't affect Free Will), but it has yet to cross over into the mainstream stories.
- The Avengers vs. X-Men Crossover averts this with a vengeance. The Phoenix Force is returning to Earth, and while the Phoenix was always an X-Men problem in the past, this time the Avengers have caught wind of it. Their disagreement on how to handle the incredibly powerful cosmic entity that could potentially save mutantkind or destroy the Earth is the main conflict of the event. It also includes the X-Men (or at least Cyclops's side) calling the Avengers out on their constantly saying that they don't involve themselves with mutant affairs even when mutants are on the brink of extinction, only to suddenly decide to get involved once the issue becomes a potential threat to them.
- One X-Men Expanded Universe novel trilogy had Magneto conquer New York City. Despite this being the home turf of Spider-Man, Daredevil, and The Fantastic Four, the X-Men are the only people (Other than the US Military) to even try to do something about it. All the other heroes who happen to live in New York aren't even mentioned.
- Uncanny Avengers is built around breaking down this trope while also giving it more reasons as to why it exists in the first place. After admitting that the Avengers never did much to help the mutant race, Captain America decides to form a new mutant-centric team of heroes in order to convince humans and mutants to get along. Problem is the two groups have different dynamics and styles of command, and they clash. Frequently. In the end the series shows at several points that this trope could also be called 'Superman Stays Out of Gotham Because He and Batman Operate Very Differently and Their Arguments Can Lead to Bad Things'. Both groups are made up of good people true, but they don't mesh as well as a pure team of Avengers or a pure team of X-Men.
- Part of the problem also originates from the membership choices. The original team had a designated leader in the mutant Havok, but Cap joining the team to inspire by example creates serious leadership confusion that often divides the team by group origins. Also the recruitment of the Scarlet Witch to the team led to several clashes with the mutant members who still blame her for House of M. While the membership was partially influenced by who they could round up during the Red Skull's plans and later by monetary and PR necessity, one can't help but wonder if the team would have had more success with a more precise and careful recruitment method that avoided conflicts of command and flare ups of old grudges.
- On the other hand, this is epically subverted in one Cable & Deadpool issue where Cable lands in trouble with the other heroes. The X-Men decide to call in help from an ally and we’re led to believe it’ll be an X-Men related character. It’s not. It’s the Silver freaking Surfer, who almost never gets involved in conflicts like this. This also highlights an out-of-story reason for this trope; Silver Surfer is so totally out of Cable’s weight class it’s almost laughable that Cable tries fighting back.
- Every year, with absolute predictable regularity, Sabretooth tracks down Wolverine on his birthday and beats him almost to death. Every year, Wolverine is totally alone and typically in the middle of nowhere on his birthday, allowing Sabretooth to easily attack him. Hey Logan, aren’t you a member of like three superhero teams? Don’t you have access to at least two fortresses full of superbeings? And aren’t you friends with some of the most powerful heroes on Earth? Do you not think they might be pretty useful right about now? This being Wolverine, he probably considers it a matter of pride to handle his own fight rather than having other people do it for him, but still.
- This trope is notably subverted in Astonishing X-Men. In the first portion of the story, the "lead" team consists of Cyclops, Wolverine, Emma Frost, Beast, and Kitty Pryde, and they are specifically attempting to build up goodwill for mutantkind by handling problems without outside help. When they head to New York City to take down a monster, the Fantastic Four show up and assist; Thing initially grouses that "they're on our turf," but Reed Richards assures the X-Men that they're happy to boost human-mutant relations however possible. In the "Breakworld" portion of the plot, every major New York-based hero gathers to try to stop the giant bullet that's on a direct collision course with Earth—but the creators of said bullet planned ahead by sealing it with various psychic and magical protections that put every single hero into a dream-like trance wherein they do successfully stop the weapon...all while their actual selves are standing stock-still. Spider-Man is the only person who's able to wake up from the spell in time to realize what's happening, but can't do anything to help because such a thing is just way above his weight class. Ultimately, Kitty Pryde is forced to pull a Heroic Sacrifice to phase the bullet through Earth, resulting in the "long story" mentioned above wherein Magneto rescues her years later.
- The X-Men's lack of presence in the World War Hulk storyline, itself a sequel to Planet Hulk, is justified via the events of M-Day. Hulk's goal in the plot is a Roaring Rampage of Revenge against the four members of the Illuminati—Black Bolt, Iron Man, Mr. Fantastic, and Dr. Strange—who decided to banish him from Earth after his powers grew too unstable. Professor X, also an Illuminati member, was not present during the group's vote, but admits that he would have agreed with the decision (although he promises that he would not have supported a permanent exile). Hulk is originally ready to take down the X-Men as punishment—and fights some of their members as well—but then realizes that the mutant population is already in crisis after Scarlet Witch's actions on M-Day. He thus leaves Professor X alone, reasoning that he's suffering enough as it is; presumably, this uneasy truce is why the rest of the X-Men don't get involved when Hulk continues his quest for vengeance against the rest of Marvel's heroes (along with the fact that the existential crisis of M-Day has shattered the group's morale and left them scrambling to stay alive).
- Both The Phoenix Saga and The Dark Phoenix Saga justifies this trope:
- In the former, the heroes learn of the M'Kraan Crystal and what it's doing to the universe, however, since the thing is way too far away for any of them to reasonably attempt any actions, all they can do is sit and wait until either it stops or the universe is blunk away.
- In the latter, the Dark Phoenix's awakening catches the attention of a lot of heroes, but it happens so fast that not even the Silver Surfer can catch up to her before she gobbles up a star. Earlier on, the Avengers headquarters does get a phone call from the Hellfire Club, but since Beast is the only Avenger around, he goes to investigate himself.
- This trope even occurs with facing threats that logically another superhero would be much more equipped to deal with. For instance, The Juggernaut is usually the X-Men's job to handle despite the fact that he's a mystically powered supervillain and thus would fall under Doctor Strange or Ghost Rider's purview, but it is extremely rare that either of them ever get involved and even when they do, it's usually just showing up to tell the X-Men how to deal with it. Strange even seems to have a working relationship with Cyttorak (given that "the Crimson Bands of Cyttorak" are one of his signature spells), the god who empowers Juggernaut, yet never takes advantage of this to stop a Juggernaut rampage non-violently.
- Fall of X: Notably averted this time. For years, the the X-Men and Mutantkind had to deal with threats from Sentinels, Purifiers, Reavers, Bastion, M-Pox, the Legacy Virus, O.N.E., and antimutant threats. For the most part, they've had to do it without help from the Avengers or other heroes, with the Avengers only intervening when mutants were threats themselves like the Brotherhood. And it's mostly been because of this trope. However, this time around, the Avengers aren't ignoring the blatant fascistic approach Orchis is taking against mutants, helping in their efforts to free mutants and even exact revenge on Orchis: Cap puts a team together and recruits Monet and Kwannon; Tony and Emma are allied against Feilong and his Stark Sentinels; Thor is seen freeing Leo Eng from Orchis mooks; and all of Alpha Flight are working as moles within the Canadian government's alliance with Orchis to ensure the safety of mutants.
- New Mutants: An early issue has Professor X give it as standing orders to the kids that if the X-Men aren't around, they are to call the Fantastic Four or the Avengers rather than try to solve things themselves. The one time they do this, the FF and the Avengers are both out, and for the same reason as the X-Men: All three teams have been abducted by the Beyonder.
