In the RS arc of Pokémon Special, the Gym leaders realize that there's a terrorist group out there planning to screw over Hoenn. Since Aqua and Magma work against each other, the Gym Leaders argue about which group are the real bad guys, not realizing that though the two teams have opposing goals, both groups are terrorists. The Gym Leaders probably would have duked it out between themselves if not for the fact that Groudon and Kyogre start destroying the region. Made worse by the fact that Tate and Liza weren't there due to their duty to guard the Red and Blue Orbs, and Norman knew better and refused to take sides. Shame Sapphire wasn't at this particular meeting, or she could have vouched against them both, being a witness to the heinous deeds of both groups.
Happens to the girls holed up in the lighthouse in the Battle Royale manga.
And they all wind up dead, especially the instigator. Oh so much.
Marvel's Civil War arc has caused this among its heroes.
So far the group in The Walking Dead comic manages to avoid this...for the most part.
The core members have learned to trust each other over the constant fear that the other people aren't making the best decisions. EVERY time someone new comes into the fold, the tension surfaces. Time, and sometimes a death or two, will put things back to 'normal'.
Used in a strip in Doctor Who Magazine in which a group of minor villains that the Doctor has previously defeated gather together in a deserted space-station to plan a final attack that will finish him once and for all. One of them dies horribly, and as the others begin dying one by one afterward, it seems (to them, anyway) as if the Doctor has infiltrated their midst in disguise and is picking them off one by one. Finally, the last couple — paranoid that either one of them could be the Doctor in disguise — kill each other... and at that point, the Doctor arrives, not recognising any of them. Turns out the first death was just an accident with a faulty machine and the other deaths were just everyone picking each other off out of sheer paranoia.
The Pocket God story arc "A Tale of Two Pygmies" revolves around this. Klik doesn't like how Ooga treats the tribe like a joke and is jealous at him for meeting the gods. When their hut burns down, he accuses Ooga of doing it and exiles him. However, Nooby and Booga go with Ooga; splitting the tribe of six into two tribes of three. Turns out the culprit was a female pygmy named Sun, who manipulated the tribe into fighting amongst each other so she can steal their Gem of Life.
The entire point of Schism was too break up the X-Men into those siding with Wolverine and those siding with Cyclops.
This was pretty much the plot of the "Home Schooling" arc of Runaways. Victor Mancha inadvertently causes a drone to crash into the Runaways' house, resulting in Klara and Old Lace getting buried beneath rubble. The rubble gets sorted out relatively quickly, but Old Lace dies and Klara loses control of her powers, burying the house in vines. The team then becomes divided over how to deal with the vines, with Chase and Victor preferring to force Klara to retract them while Karolina, Nico and Molly prefer to wait until she's calmed down enough to retract them of her own free will (eventually, Nico uses a magic spell that tranquilizes Klara, but this angers Molly, who considers forcing someone to sleep against their will to be abusive.) Further complications arise when a paramilitary unit arrives to investigate the attack, causing the Runaways to flee the house while Chase abandons the team. Apparently, the arc was supposed to end with them being reunited by a suddenly-revived Gert Yorkes, but the series was cancelled halfway through the arc...
In Night of the Living DeadBen and the Mr. Cooper fight over the use of the cellar. Ben believes it should just be a last option, with Mr. Cooper thinking it's their only option and threatens to close everybody else out of the cellar if they don't make up their mind. Eventually things come to a boil in both versions of the film. Unfortunately, it turns out that Cooper may have been right. In the underrated remake Ben and Cooper get into a shoot out within the besieged house over the fact that Cooper wouldn't let anyone kill his daughter.
Also averted, partly because they were Genre Savvy enough to know about it.
In John Carpenter's 1982 version of The Thing (1982), The researchers at Outpost 31 turn on each other when they realized the alien could imitate anyone. Paranoia and intense tension build up, Resulting in one of the most bone chilling endings ever made.
The 1951 version, The Thing from Another World, centers on a conflict between the scientists and the military over how to best deal with the alien creature (which is a more conventional monster rather than a shape-shifter).
Partially subverted in Saw V, in that Jigsaw not only does nothing to promote his captives' squabbling, but arranges things so that cooperation would've greatly reduced the casualties. Too bad the prisoners were so determined to act this trope out straight...
Shaun of the Dead - Shaun: As Bertrand Russell once said, "The only thing that will redeem mankind is cooperation." I think we can all appreciate the relevance of that now.
Cube. Although the eponymous Cube is filled with lethal booby traps, they only kill two of the seven characters.
The Descent. Mostly between Sarah and Juno, especially after the former found out the latter took the group caving/spelunking in a dangerous uncharted cave that's filled with flesh eating subterranean mutants, in a misguided effort to reunite the group. Not to mention the fact that Juno also slept with Sarah's deceased baby daddy. Juno's Good Intentions not only contributed to her friend Sarah's breakdown . But also led her friends to their doom.
Juno also accidentally mortally wounded one of her friends (Beth) in the cave thinking she was one of the cave dwelling monsters. And left her there to die and tried to cover it up. When Sarah comes across the injured Beth, Beth explains what happened (including info about the affair Juno had) . And tells Sarah not to trust Juno, essentially putting the proverbial nail in the coffin of Sarah and Juno's friendship.. Of course karma is a bitch, as Juno sufferers the consequences(unfairly or not).
A literal example (well actually an apartment complex) in the films [REC], and Quarantine. The inhabitants never fully reach this level seeing as how the infection happens so fast people rarely get the chance to argue with one another. Although they came DANGEROUSLY close to this trope during the initial panic.
The Beast Of War is a forgotten war movie from 1988, depicting the struggle between a Soviet tank crew and their mujahadeen opponents. Not all the conflict takes place outside the tank. The commander shoots his Afghan translator, convinced he's working with the enemy, and when another soldier threatens to report the killing he's tied to a rock and booby-trapped for the mujahadeen to find.
The Stephen King story and movie, The Mist. A military project codenamed 'Operation Arrowhead' has gone awry and a quaint Maine town is shrouded in mist that happens to be filled with flesh eating monsters from another dimension. A lucky few residents are able to barricade themselves in the local supermarket. The Fundamentalist Mrs. Carmody preaches that this is all an act of God for landing people on the moon and homosexuality. Yes, really. Yet as people start getting picked off by the monsters most of the people in the store let their fear get the better of them and start listening to Mrs. Carmody's sermons, save for a level headed group that finds its self outcast and fearing for their lives after Mrs. Carmody has her followers sacrifice one of the townspeople to the monsters. When they decide that they would rather face the monsters then face a religious nut, Mrs. Carmody tries to stop them and utters her final words, 'Kill them all!' before she is finally put in her place with a Boom, Headshot.
Happens to a small group of teenagers on a plane in the film Altitude.
Survival of the Dead. Only it's more like an island divided. The O'Flynns and the Muldoons have such a sharp family rivalry that they don't even pay attention to the zombies killing everyone around them during the final showdown at the end. And they don't let up, either. Not even when they become infected themselves. Tsk, tsk.
M.Night Shyamalan's Devil takes this beyond the average person's tolerance with an elevator full of people slowly being killed off.
The post-apocalyptic film The Divide is fueled by this trope.
The story Who Goes There? by John W. Campbell, which provided the inspiration for the movie The Thing (1982). A shape-shifting alien is thawed out, and proceeds to start killing people in an isolated Antarctic research station. Everybody is understandably paranoid and scared to death. Besides being eaten to death of course.
In the Stephen King short story "The Mist", this happens to around 80 people stuck in a supermarket. The main threat is a deeply religious woman who urges the others to make a blood sacrifice to stop the monsters outside.
Will Navidson and his significant other Karen move into the house because they are trying to avert this trope, but the strange happenings in House of Leaves don't allow for that sort of healing.
In Terry Pratchett's Discworld, wizards have a weird, formalized version of this. Wizards get along about as well as a sackful of soggy cats, something apparently programmed into them at a genetic level (or at least the level that passes for genetics on the Disc). Unseen University was created to redirect that murderous energy into a strict hierarchy where a cutting note could do nearly as much damage to one's opponent as a hurled fireball, but with a much smaller risk of bystanders being turned into charcoal (or possibly haddocks). They still cheerfully murder one another with creative booby traps, but things have settled somewhat now, since the current head of the University has proven himself more or less unkillable (and he sleeps with two loaded crossbows, although he's a kind man, and probably won't shoot you in both ears).
Machiavelli in Discourses on Livy believes that this is one of the reasons for a republic's strength, since it allows the right leader to come tot he fore at the right time.
Seen in Star Trek: Gemworld during a crisis, when the six races of Gemworld, and their leaders, fail to work together succesfully. Barclay calls them out on it, by appealing to the Good Old Ways:
"This is not how your ancestors survived, by ignoring a problem...The inhabitants of Gemworld have gotten soft. You prefer to bicker and fix blame instead of finding a solution. I'm sorry...that's not how the Ancients would have faced this ...The question is - will you act like your ancestors? Will you do what it takes to survive? Or would you prefer to hide in this room and bicker?”
The good guys in Tolkien's works are all too prone to this. The elven factions in Beleriand are one example. Another would be the mistrust between Arnor and Gondor, and the various succession crises, secessions, and outright civil wars within the realms, which give Sauron opportunities to weaken and (in the case of Arnor) eventually destroy an enemy he couldn't take on all at once. It looks like the Ring-war is going the same way (Rohan occupied with internal problems, and the southern fiefs of Gondor reserving most of their manpower to defend their coastlines) until Gandalf and Aragorn shake things up.
In the first Hunger Games novel, it's mentioned that this usually happens to the Career tributes. The Careers typically work together in the beginning of the games to set camp, protect each other and kill as many of the non-Career tributes as possible early on. However, since there can only be one survivor in the end, as soon as there are so few non-Careers left that the Careers don't really have a common enemy anymore, distrust and disapproval starts spreading among the group, until they inevitably turn on each other.
In Undead on Arrival the rival gangs that control Devon seem more concerned with killing each other than the hordes of zombies.
In Babylon 5, the alliance against the Shadows turned in against itself when it was left leaderless by Sheridan's death. Order was only restored when the Messianic Archetype returned from the dead.
Happens from time to time on LOST. Often a main character will stop the fighting and remind everyone that there are other threats to their survival without them turning on each other. Jack, Locke, and Hurley have delivered such speeches, beginning with Jack's "live together, die alone" speech in an early episode.
One interesting example, from season two: Sawyer and Michael, essentially Locked in a Room on the wreckage of their raft, start bickering about whose fault it was that Walt was kidnapped by the Others. This becomes the issue that their being Locked in a Room allows them to overcome.
Pretty much the entirety of "Midnight" is an extended Scorpion Box. it's easily one of the most disturbing Doctor Who episodes ever aired.
Also the plot of the First Doctor serial, "The Edge of Destruction".
The Twilight Zone episode "The Monsters Are Due on Maple Street".
The Outer Limits episode "Abduction", An alien kidnaps five high school students, and tells them that one must be killed. They must decide which of them it will be. And of course they're from completely different social groups. Ray, a typical jock, Danielle, the hottest girl in school, Jason, a stereotypical geek, Brianna, a devout religious girl, and Cody, a social outcast. So needless to say they don't get along. But then again it was a test. And the ensemble was picked for that very reason.
The 4400 episode "No Exit" features most of the major characters being Locked in a Room... that's trying to kill them. Their bickering and political differences lead to Shawn and Meghan's deaths, and in the end Jordan and Tom need to work past their personal differences to save the others.
Also happens in the Buffy the Vampire Slayer episode "The Yoke Factor" when Spike turns the Scoobies against one another.
In the Haven episode "Real Estate", the house is a malevolent Genius Loci that uses the characters' pre-existing tensions against them, culminating in a three-way Mexican Standoff.
Came up in "The Ship", when Captain Sisko and crew have to take shelter in a crashed Jem'Hadar fighter while more Jem'Hadar are shelling their position. Most of the tension is between O'Brien and Worf over how to deal with a dying Red Shirt (O'Brien wants him to keep fighting for life, while Worf implies killing him to spare his suffering), though everyone gets into the act.
Sisko: I know it's hot. We're filthy, tired, and we've got ten isontons of explosives going off outside. But we will never get out of this if we don't pull it together and start to act like professionals!
Game of Thrones is this Turned Up to Eleven. The whole realm is at war with one another over the iron throne, while a greater threat of "snow demons" with a hoard of "snow zombies" mobilizes in the north.
This was offered as the main reason the nWo was so successful against WCW; the WCW wrestlers were a bunch of gloryhounds with a ton of unsettled issues against each other and a desire for the spotlight, while the nWo operated like a well-oiled machine.
Warhammer 40,000's Imperium intentionally invokes this trope with every institution, organization and military unit mistrusting everyone else. This does leave them with a bureaucratic nightmare where military or humanitary aid for worlds may arrive a century after it was needed, but it also keeps the human race comparably safe from the danger of a high-ranking defector. This lesson was learned after two bloody civil wars, one of them tearing humanity out of its beginning golden age.
This also happens to foster an environment where different parts of the military occassionally go to war with each other, however...
Then there's the Realm in Exalted, now that the Scarlet Empress has vanished. The Anathema are on the loose, new and sinister forms have emerged, one Realm outpost has been conquered by a Deathlord, the Bull of the North is on the rampage, and the most likely outcome within the Realm itself is all-out civil war over the Scarlet Throne.
Happens regularly in BattleTech, the five great houses generally have infighting among themselves from time to time. The most prominent example is House Marik, which broke up into four factions after the Jihad. The Clans sometimes have this, they are divided into two groups the Crusaders, and the Wardens who have conflicting views on Kerensky's legacy.
In Danganronpa, the villainous headmaster Monokuma informs his students that the only way to graduate Despair Academy is to murder one of the others without getting caught. On top of this, he gradually introduces extra motivation, leading to more paranoia as nobody can be sure who's going to try and get out.
A subversion of the villainous version happens in Survival of the Fittest - Burton Harris/Ken Lawson plays off the paranoia and reservations of a group of students hanging out in a cottage in order to get the entire uneasy alliance to dissolve. Burton/Ken wasn't exactly a villain though, just a dick who thought that the place was too crowded.
The Trolls from Homestuck eventually become this, as shown by this update and the ones following it. They start off with twelve. Currently, they're down to four (five and a half if you include Aradia and Sollux), and Kanaya expresses an interest in making it three.