One Piece, but not if you are a main character: your Bad Ass status allows you to be supportive or enemy of the World Government with abandon. Neutral countries, on the other hand, have to accept Government leadership, or their whole population will be deported and enslaved. Because the alternative is pirates, so...
The Atlantic Federation of Gundam SEED does this with regards to Orb. Orb has a mass driver, which the Atlantic Federation needs, so they give them this trope as an ultimatum*
Admittedly, this was done mainly by Muruta Azrael; the other leaders of the Atlantic Federation were very reluctant to go along with it
. It happens all over again in Gundam SEED Destiny, (albeit done by Blue Cosmos / Logos this time) when the Destroy Gundam is unleashed on the western Eurasian Federation for being too sympathetic to ZAFT. Durandal also pulls this at the end of the series, stating that anyone who doesn't agree to his Destiny Plan is a threat to world peace, in with the aforementioned terrorists and deserve to be eliminated via Kill Sat.
In the Shaman King anime, this is the reason the X-Laws hunt down Yoh and his friends. Like Marco said, they become "too powerful to let [them] be."
In the Chick Tracts, anyone who does not agree with Jack Chick's particular breed of fundamentalist Protestant Christianity is doomed to burn in hell. Even other Christians who have slightly different views are completely evil.
When Steve Ditko took a heavy turn into Objectivism, his heroes started to preach his viewpoint. That "Mr. A" Alan Moore sings about? That was one of Ditko's, who claimed that man can either be good or evil with no in-between.
Spider-Man: Brand New Day has The Extremist. To him, you are either with the heroes or with the villains, and anyone who dares to criticize superheroes or even laugh at them is evil and schemes to blur the line between good and evil— and therefore, must be eliminated *
. He even tried to kill the guy who made a website dedicated to laughing at Spider-Man— who happened to be Peter Parker.
Films — Live-Action
Parodied in Monty Python's Life of Brian, where the splinter groups against the Romans hated each other as much as the Romans. While this was originally intended as a satire on the increasingly-fractured British Left in the late '70s (the Pythons were all for Labour at the time, although John Cleese has since become a Lib Dem), it turns out that the Jews in Jesus' day really were quite fractured and always squabbling against themselves instead of the Romans.
The page quote is from Revenge of the Sith. When Anakin throws that line at Obi-Wan, he simply responds, "Only a Sith deals in absolutes" (which, ironically, is itself an absolute) and ignites his saber to take this murderer down.
In Ben Hur, this mentality is what drove Messala to sentence Judah Ben-Hur to slavery. Messala wanted his friend Ben-Hur to turn in the Jews who were speaking against him and the Roman occupation. Ben-Hur refuses, so Messala tells him, "You're either with me or you're against me." Ben-Hur replies, "If those are my choices, then I am against you."
Given that is was made in The Fifties, this is likely a reference to McCarthyism, in which many Hollywood people were ruined for declining to name Dirty Communists alleged to be among them.
Avatar: Colonel Miles Quaritch while fighting Jake Sully at the climactic battle of The Tree of Souls.
"Hey, Sully, how does it feel to betray your own race? You think you're one of them? It's time to wake up."
The world in the Apocalypse film series is divided into who's believing who is God: Franco Maccalusso or Jesus Christ. Neutrality on the issue is brutally dealt with by the One Nation Earth agents and officers.
In X-Men: First Class, Sebastian Shaw expresses this sentiment:
If you're not with us, then you are, by definition, against us.
In The Rock, Captain Frye makes this claim to Major Baxter during the Mexican Standoff. Baxter hesitates, then draws on General Hummel, but spins and shoots Captain Darrow instead. He takes a bullet for his trouble.
The concept of "War is Peace" in 1984 boils down to this trope.
In the Sword of Truth series, one of the explicitly stated Aesops is that our lives are our own, and we should do with them as we choose. Not a horribly warped lesson, right? Yet Goodkind turns this into a Broken Aesop with parts of the rest of the books that claim the only "real" choice for our lives is to fall in line with his views, and that any other choice just makes you as wrong than the bad guys. Even if people have been lied to all their lives, like the Hakens in Soul of the Fire, they either side with Richard, or they have crossed the Moral Event Horizon, and should die like the evil swine they are.
Similarly, the bad guys' whole belief system is based around the exact opposite idea, that your life should be spent only serving others, and if you are special in any way or, God forbid, try to enjoy life, you deserve everything the evil army is going to do to you. In fact, it's not so much "any other choice makes you wrong," as the only choices: Side with Richard (and probably be steamrolled by the Order anyway), be willingly oppressed by the Order and (probably) live, or get caught in between them and die either way. This is a world with no middle ground.
And any nations or cities that chose neutrality in this war get the worst fate. In short, the series, from the time the Imperial Order shows up, is one long False Dichotomy.
Except in this particular setting the dichotomy isn't false at all: Though Richard is perfectly willing to live and let live, his enemies are implicitly not. One's choices are thus limited to "resist or serve" - if you refuse to choose a side, the good guys will leave you alone, but the bad guys will be able to hit you exponentially harder due to your lack of good guy support. Kind of like World War II.
Invoked by both sides near the end of Deryni Checkmate, during the acrimonious Interdict debate in the Curia which began the schism in the Gwyneddian Church. At one point, Cardiel addresses a couple of junior bishops: "Siward? Gilbert? Do you stand with us? Or with Loris?" Loris finally hangs the lampshade when Cardiel (host of the assembly in Dhassa) orders him to leave: "Then it is war. And all who side with the enemy shall be counted as the enemy. There can be no other alternative."
In The Illuminatus!! Trilogy, Hagbard Celine says, "People who say, 'You are either a part of the problem or a part of the solution' are usually the former."
In Thud!!, the narrator discusses the increasing dwarf/troll conflict and its effect of causing dwarfs and trolls to resign from the watch:
Some people would be asking: Whose side are you on? If you're not with us, you're against us. Huh. If you're not an apple, you're a banana!
In The Thrawn Trilogy, Borsk Fey'lya sees his political rivals as his enemies. He's not above leaving them to die, and thinks that everyone else thinks in similar terms. Thrawn in fact counts on Fey'lya acting this way to paralyze the New Republic and dispose of the people who pose a real danger to him, like Admiral Ackbar.
It's a trait that most Bothan share. Bothan society is based around a system where the pursuit of power and influence were paramount, and it was quite normal to use backstabbing, political maneuvering and character assassinations against others to gain influence. However, they usually only did it within their own society; Borsk was unable to see that other races didn't operate this way. Thrawn, having analyzed species' psychology based on their artwork, knew and took full advantage of it.
Belgarath defines the battle at the core of the Malloreon as "them and us" at one point (as opposed to "good and evil", which he considers a dangerous game to start playing).
In A Song of Ice and Fire Melisandre believes that people either are on the side of her god R'hllor or that of the Great Other. She uses the analogy of a half-rotten onion to prove to Ser Davos that a man who is half-evil is still evil, not good.
In the Left Behind books, during the Tribulation, it eventually comes down to joining God or joining the Global Community, as both sides end up squashing any sign of neutrality on the issue.
In Darkness At Noon, Rubashov recalls having enforced the principle that not to be absolutely with the Party was to be against the Revolution, and realizes he is doomed by that same principle now that the Party has decided to destroy him.
Live Action TV
The basis of Stephen Colbert's life philosophy. "You're either with us or you're against us. It is either Coke or Pepsi. You're either gay or you fight it." Finally he states he divides the supermarket into "cheese" and "not cheese". He also tends to badger people, including guests, who do not fall into one of his two categories, with "Pick a side—we're at war."
Star Trek: Deep Space Nine: Commander Kira tells this lesson to the Cardassians when they've started a rebellion. She's reminded in the same episode that Odo (her lover) used to be against the Bajorans while the Cardassians were occupying her planet.
Also, Kira to Odo: "We used to have a saying in the resistance, 'If you're not fighting them, you're helping them.'" Kira holds a very dichotomised view of "collaborators", particularly in the days immediately after the Cardassian Occupation, and one which is challenged on several occasions through the course of the series.
In The Darkness and the Light members of her former terrorists cell were killed. Eventually she found that it was a Cardassian wounded in one of their bombings seeking revenge. He stated he'd been a civilian servant, not involved with the crimes against Bajorans, and worked in a building they bombed. Kira doesn't care-she considers them all guilty, as none of them should have been there on Bajor to begin with. Yes, there is a reason she admits to being a former terrorist...
Although later in the series she does learn to be bothered by it when it's pointed out that Odo worked for the Cardassians, even after he learned that they had no real interest in "justice", and was therefore a "collaborator" by the very vague definitions she used.
Russel Hantz tried this phrase on Sandra during Survivor : Heroes Vs. Villains. Backfired spectacularly when Sandra immediately told him she was against him, something those on the Survivor Jury loved.
'Which Side Are You On?' by Natalie Merchant.
They say in Harlan County
There are no neutrals there
You'll either be a union man
Or a thug for J. H. Claire
The Bible: God Himself insists that You are are either With Him or Against Him.
Example: Luke 11:23 ' "He that is not with me is against me: and he that gathereth not with me scattereth." But in Luke 9:50 "Jesus said to him, "Do not hinder him; for he who is not against you is for you." Luke recounts both these which are attested in Mark and Matthew separately. One resolution of the problem is that Jesus thought anyone should be allowed to perform good work in his name so be inclusive, but on ideology you should be exclusive. Or the first is applied exclusively in "gathereth" vs. "scattereth" context.
An unfortunate example happened with TNA Wrestling president Dixie Carter, giving a big speech to the wrestlers before an episode of iMPACT! in which she acknowledged the awful decisions being made by the company, and rather than do anything about it, told the wrestlers to shut up or leave. Either they were behind her, or they could leave the company. Thisdidnotgooverwellwithanyone at all.
Warhammer 40000 demonstrates what happens when you mix this trope into a setting that runs on Black and Grey Morality. The results, from the Imperium of Man and Tau Empire, are not pretty. And in the Horus Heresy novels, this kind of view is expressed by many who are joining the traitors.
Tarik Torgaddon: If those are my choices, then I am against you.
Forgotten Realms has a paladin Order of Samular. Once they hunted a demon and an elven community that happened to be between them — surprise! — didn't allow a little army of human heavy cavalry to crash through their territory just so... "thus allying themselves with the evil tanar'ri". More than a generation (human) later elves were still upset about the resulting bloodbath and paladins "wary of elves and their unknowable, inhuman ways".
The Crucible: "A person is either with this court or against it, there be no road between."
In A Man For All Seasons, Thomas More does not like King Henry VIII's actions, but rather than complain, he keeps his mouth shut and refuses to say anything one way or the other. Unfortunately, Sir Thomas is widely known as one of the wisest and most honest men in the kingdom, and his silence makes his position on the issue pretty obvious to everybody. King Henry then lays down the gauntlet, and makes everyone in England swear an oath affirming his support of the King's actions, prompting the film's main conflict.
In Dragon Age II, tensions between the mages and the templars in Kirkwall reach a peak when Anders blows up the Chantry that Hawke is forced to either side with the mages and protect them from the templars or side with the templars and exterminate the mages.
By Act III, Meredith is so paranoid that she believes that anyone who disagrees with her is a blood mage's slave. She refuses to acknowledge the possibility that her fellow Templars might disagree with her entirely of their own free will. You're either with her, or with the blood mages. This gets even more pronounced when she whips out her lyrium idol sword, which was the cause of Bartrand's insanity and also what pushes her to the edge.
By the end of the game, Anders has deteriorated to the point that anybody who does not explicitly share his exact opinions on mage freedom fighting is just as bad as an enemy. It's difficult to say how much of this is from Anders himself and how much comes from Vengeance.
The AI in the Civilization series often act like this: trade with them, or be considered enemy, trade with their enemies and also be considered enemies. This is particulary visible in IV there its near impossible to stay neutral unless you have the forces and tech advance so noone want to wage war against you anyway, except you have a different religion as Isabella, who envokes the With Us or Against Us on your state religion.
Ulfric Stormcloak of Skyrim is like this. In the words of Jarl Balgruuf:
Balgruuf (paraphrased): To not fight with him is to side against him!
To Ulfric's credit, he understands that people in general have more nuanced reasons for not necessarily joining his cause. On the other hand, his second-in-command, Galmar, quotes this trope nearly verbatim
Jarl Balgruuf of Whiterun is desperate to try remain neutral in the conflict. When first asked what side he supports, he replies "Whiterun's". He eventually is forced to choose, however and lends his support to the Empire.
After a certain point in the main quest the Blades discover that the Dragonborn has been working with Paarthurnax, who is a dragon and the former right hand of Alduin, and they refuse to cooperate with him any further unless he kills Paarthurnax for his past crimes against mankind. The player doesn't have to do this to finish the main quest, but the Blades cannot be convinced to let their grudge go.
Delphine: It's your choice Dragonborn: us or him.
The Scarlet Crusade of World of Warcraft believes its holy purpose is to destroy the Scourge. However, they believe that anybody who has not joined the Crusade is likely a carrier of the plague and is thus their enemy as well. Only when preparing to face Kel'thuzad have they grudgingly worked alongside other groups.
Garrosh officially adopts this philosophy as of Tides of War, declaring that all members of the Horde, even those who aren't in a military occupation (including civilians and shopkeepers) must swear absolute loyalty to him and him alone, or be put to death.
Rick: Your theory is a nice start, but I can break down my feelings even further. I have identified two basic emotions. Scott: Really?! Just two?! Rick: Yes, "anger" and "not anger." It used to be three emotions, but I eliminated "less anger."
Gaston in Beauty and the Beast, when he's roused the villagers into a Torches and Pitchforks mob against the Beast while Belle is trying to talk some reason into them ("If you're not with us, you're against us!").
Zapp Brannigan in Futurama views the Neutral Race this way. "With enemies you know where they stand, but with Neutrals, who knows?" Therefore he decides to crash the Planet Express ship into their capital. "Another heroic battle in the war between Good and Neutral!"
Demona says this in the pilot of Gargoyles: "If you are not my ally, then you are my enemy."
Lock-up in Batman The Animated Series actually says, "If you're not part of the solution, then you're part of the problem." (Throughout the episode, he also blamed the "liberal media," as well as "gutless police, mindless bureaucrats, and coddling doctors" for society's problems, so he's really more of an outright criticism of conservative argumentation.)
In one episode of Daria Jane begins dating a guy named Nathan who is really into 1940s nostalgia, to the point that she begins dressing in 40's styled clothing on a daily basis. Eventually, Nathan proves to be a Straw Fan after his passive aggressive insults to Jane's clashing wardrobe leads an exasperated Jane to state "it's a fad, it's just for fun." Nathan counters about how he's one of the true believers left after everyone else moved on to a new fad, and Jane is either with them or against them. Jane kicks him out after he makes a disgusted comment about her owning sweatpants.
This is one of the central ideas of the Objectivism philosophy upon which The Sword of Truth, see above, draws heavily. "A is A" and all that—see the quote above. Ayn Rand, the philosophy's founder, was a lot like this in real life—if you disagreed with her even slightly, you were out of her little collective. As she stated: 'When a man declares: "There are no blacks and whites [in morality]" he is making a psychological confession, and what he means is: "I am unwilling to be wholly good—and please don't regard me as wholly evil!"' Although this was more to do with the theory of morality associated with the philosophy than "being a part of her little collective", that there is only good and evil but not quite-good and quite-evil or slightly-good and slightly-evil.
Some laws have it as a required concept that this is sometimes if not always the case. If you welcome a distressed family member into your home, feed them, try to help them calm down, and then later find out that they are on the run from the cops, you have two choices. Report them to the cops, or be legally considered an accessory after the fact to whatever crime they have committed. (However, some jurisdictions will allow you to protect family members without punishment.)
A very slight extension of this extends to states who harbor elements like Al Qaeda. President George W. Bush used the Trope name in a speech speaking to other nations, stating that if they willingly harbored the enemy, they would be considered the enemy. He hardly invented that line of reasoning: it's always been an act of war to willingly give one of the belligerents in an ongoing armed conflict safe harbor in your nation. That's why neutral powers during wars are required to intern combatants of either side that stray into their territory.
George W. Bush famously said, "Either you're with us, or you're with the enemy; either you're with those who love freedom, or you're with those who hate innocent life."
Which then caused him to be called a Sith Lord (Not kidding here!) by some newsgroups.
As mentioned earlier, Message Boards. This mostly applies to religious and political boards, but can (and usually will) extend to everything else. Anyone who has spent enough time on boards will know that there's often topics where you either agree with a completely insane statement or you're branded as whatever is the opposite of the poster's ideology/beliefs/whatever (examples of popular insults: communist / selfish capitalist, Satanist/superstitious nutjob, far-left/far-right, homosexual / homophobe [this one usually appears just for opposing ANY opinion]). Trolls are often to blame for this.
In Canada, the federal Public Safety minister tried to bully criticism about a pending online snooping act with the line "You either stand with us or the child pornographers" in the House of Commons. This statement caused howls noting that he is smearing every provincial Privacy Commissioner who expressed deep concerns about the bill and provoked online retaliation with many people twittering their minute personal details to the Minister while another threw all the court info of his messy divorce online.
During the Rwanda genocide, moderate Hutus were targeted in addition to the Tutsis.
Bernadine Dohrn, a prominent member of the Weather Underground during the Black Power movement and the protests against the Vietnam War, famously stated: "White youth must choose sides now. They must either fight on the side of the oppressed, or be on the side of the oppressor."
In 1956, Hungarians revolted against the harsh Communist dictatorship. The revolution was crushed by Soviet troops, but a much milder regime was established under János Kádár. In 1961, he inverted this statement, saying that "whoever is not against the People's Republic of Hungary is for it."
One of Ghenghis Khan's winning strategies, thus why he is the Trope Namer for Genghis Gambit. The ones who joined up became his friends who helped him obliterate the ones that refused.
Neutral or indifferent parties tend to universally be the victim of this as they frequently get the brunt of the grief from both sides. Sometimes it actually will stop them from being indifferent or neutral... by frustrating them into Taking A Third Option and becoming hostile to both.