"A nation can survive its fools, and even the ambitious. But it cannot survive treason from within. An enemy at the gates is less formidable, for he is known and carries his banner openly. But the traitor moves amongst those within the gate freely, his sly whispers rustling through all the alleys, heard in the very halls of government itself. For the traitor appears not a traitor; he speaks in accents familiar to his victims, and he wears their face and their arguments, he appeals to the baseness that lies deep in the hearts of all men. He rots the soul of a nation, he works secretly and unknown in the night to undermine the pillars of the city, he infects the body politic so that it can no longer resist. A murderer is less to fear. The traitor is the plague."
— Attributed, possibly falsely, to Marcus Tullius Cicero
Named after Vidkun Quisling, who assisted the Nazis in their conquest and rule of Norway during World War II. The poster boy of Les Collaborateurs, he (and it's almost always a man) appears whenever one country or culture is being conquered, occupied, or colonized by another. He does everything possible to curry favor with the new rulers. He speaks their language more often than his own, apes their customs and refers to his hometown as New Invaderia instead of Freedomville. He might justify this on the grounds that by securing a position of power and influence he can ensure the occupation is as painless and least oppressive as possible. Sometimes, he will have been a friend of the heroes before the invasion, but often he will be someone who had always given our heroes a hard time, and he will try to make them "see reason" and stop their futile attempts to restore the old regime. Frequently has elements of the Obstructive Bureaucrat or The Dragon. When conversing with the conquering leaders he will probably be Opinion Flipflop personified.
Despite all this, the Quisling is never seen as an equal by the conquerors, but at best as a useful tool to keep the natives in line. At worst, they hold him in almost as much contempt as his own people. Either way, they won't hesitate to dispose of him once he's outlived his usefulness. If the invaders value honor, expect him to eventually get killed BECAUSE he's a betrayer to his cause: at least the other invaded have a sense of pride and honor!
What distinguishes the Quisling from other Collaborateurs is authority. A Quisling will never be considered an equal by the conquerors, but he will have a position of power that will be used to influence the conquered people. He will often be the local "poster boy" for submission to the conquerors. If a character has a minor job within the conquerors' hierarchy or simply chooses to accept the conquerors' rule rather than resist, then they are Collaborateurs but are not Quislings.
His storyline tends to end in one of a handful of ways:
The first against the wall when the revolution comes. Disposing of or disgracing him is one of the first major victories for La Résistance, and now the real struggle begins as the invaders start to take those rebel scum seriously...
As the rebellion grows and its victory draws near, he opportunistically switches or is coerced to switch sides. He's disgraced and held in even more contempt, but is just useful enough to save his neck.
He finally does a Heel Face Turn and joins La Resistance for real, becoming a redeemed hero in the process (though expect redemption to equal death in a lot of cases). Most common when his apparent betrayal is really because he's been trying to moderate the oppression of the invaders, and they finally go too far.
He was actually the Secret Identity of La Resistance's leader all along, playing a dangerous double game to act as a Reverse Mole. He might still be vilified in the histories, but the heroes will remember his name with honor.
The first against the wall when the revolution ends, as the newly freed heroes are only too eager to convict the heinous traitor in a court of law (or just lynch him in the street). This is what happened to the historical Quisling, as the Norwegians re-instituted the death penalty just to apply it to him.
The revolution fails or is temporarily crushed, and he's killed, "purged" or otherwise done away with, anyway, because the higher-ups don't trust a former member of the conquered nation (let alone a traitor).
Humorously averted by the Chick-fil-A Cows, who ask that America "EAT MOR CHIKIN".
Chick-fil-A had previously had an anthropomorphic chicken for a mascot; its switch to cows was widely seen as a wise move, in part because this subtrope leads people to think that anything with cows would be for milk, or perhaps beef... nope.
Anime & Manga
Busou Renkin has "familiars", humans who serve the hommunculi and will mark themselves with the same insignia to avoid being eaten by them.
Suzaku in Code Geass, who ingratiates himself thoroughly into Britannian culture after becoming the Knight of Seven. And later the Knight of Zero, right-hand man to the new Emperor...his childhood friend, Lelouch. Who he helped dismantle the empire entirely. But since their plan involved Lelouch building an image as the worst dictator in history, and Suzaku seeming to die in service of that dictator, all but the small handful of people who figured out what was happening will remember him as nothing but a traitor.
A very strange and unique example of this comes from the Crest of the Stars franchise. Ghintec/Jinto starts out a little ambivalent about the centerpiece Space Elves of the work, the Abh, but by the start of the second "season" of the TV series he's unflinchingly loyal to the Abh and their conquering empire (in part due to, uh, his loyalty to Lamhirh/Lafiel, one of the princesses of the Abh). The people of his own world definitely see him (and his dad) as examples of this trope in-show and it causes a lot of trouble later on. The unique element? Ghintec is our hero and point-of-view character.
Becomes a big plot point in Banner III, when Jinto's foster parents (leaders of La Résistance) attempt to convince him to defect. Jinto points out that he can't defect, as he's the only thing standing between them and annihilation by the Abh. (Although his mother suspects it's really about the girl he brought home to dinner with him). It's all very tragic. Leads to Jinto's foster mother pleading with the Abh princess Lafiel to take care of her son. Her response was poetic and quite moving.
It's actually lampshaded, when Jinto wonders if he had met other Abh before Lafiel, would he still be on the side of the Abh?
George Sairas (President Chicken-Maggot) in Death Note.
The mayor of Shinjuku in Karas fits this trope, cheerfully doing Eko's bidding—and even believing in his philosophy.
Sailors Neptune and Uranus in the final season of Sailor Moon give up their star seeds willingly to Galaxia for power, gladly fight their own friends and teammates, and even kill 2 of the others Sailors Pluto and Saturn. This is a gambit on their part to use their powers to capture Galaxia's own star seed. It fails miserably because Galaxia is Genre Savvy enough to see through the plan.
Not true - Galaxia even says they managed to fool her. The gambit works perfectly, with one minor snag: Galaxia doesn't have a star seed.
In Fullmetal Alchemist the entire upper echelon of Amestris's government is composed of Quislings. They all secretly serve an inhuman being bent on killing everyone in the country, being promised immortality in return.
Eggman does this a bit during the Metarex Saga of Sonic X... that said, he doesn't do an entirely terrible job of it and is out for himself from beginning to end.
Cassius Ceramix in Astérix and the Big Fight is one played for laughs: he forces his village to adhere to Roman customs to an absurd degree (for example, he orders an aqueduct to be built in the village despite a river running right through it. When someone points this out, he orders that the river be diverted because "aqueducts are more ROMAN!") and addresses the Roman Villains of the Week as "our beloved invaders."
The original film has Mayor Bates of Calumet, Colorado, as a reluctant collaborator, especially given that the Soviet and Cuban occupiers are shooting his townspeople in retaliation for the guerrilla actions of the Wolverines. Despite this (or maybe because of it), he turns in his own guerrilla son to the KGB, who force him to turn traitor (for which he gets executed by his friends). It's never shown what, if anything, happens to the Mayor.
Likewise in the remake the mayor of Tacoma, Washington is also one, but only because he is entirely concerned for his citizen's own safety and well-being. He doesn't like the invasion, but he knows that the best thing he can do is to make the transition as easy and peaceful for his people as possible. When the time comes that the mayor may end up being killed in a Wolverine operation, the mayor's son apologizes to himself and says that it's for the greater good.
The reverse-mole type of Quisling is exemplified by Tom Reagan in Miller's Crossing. Cast out by Irish-mob boss Leo O'Bannon for fooling around with Leo's mistress, he joins up with Johnny Caspar's rising Italian-American gang, but only to take Caspar down from within and save Leo. A Campbellian (Joseph, not John) heroic archetype: To save his own side he sacrifices his honor; this is pointedly an irreversible sacrifice. At the end Leo invites Tom back in the fold but he can't accept.
Two examples from the German film Novembermond: Played straight with a male character who fits the Les Collaborateurs trope, and pretended at by Fèrial to act as a Reverse Mole.
Although it might not count, since he probably wanted to cook the cast anyway, in Muppet Treasure Island, when the heroes land on the island of "cannibal pigs", the Swedish Chef gets a cameo (which the Singing Fruit break the fourth wall to lampshade) in which disguised with a fake pig-nose, he serves as the chef for the pigs.
Many of the former Dead Rabbits in Gangs Of New York, but especially Happy Jack Mulraney, who had become one of Bill the Butcher's most valuable men, and whose death marks the return of the Dead Rabbits.
Ip Man, starring Donnie Yen, has a normally Wiggum-esque police chief become this when the Japanese invade China.
Transformers: Dark of the Moon has Dylan and his late father, from whom he inherited the Decepticons as a "client".
He actually takes this to confusingly extreme measures, suggesting they kill their Autobot prisoners and fighting tooth and nail for the Cons to win, even though it's pretty clear the Autobots are winning and they don't really care much for his deal with them to begin with so he'd be safer just letting the Autobots win. Then Fridge Brilliance sets in and you realize that he'd rather die than have the Cons lose, because after what he did he'd be considered a war criminal for assisting aliens in enslaving his own species. Comic backstory goes even further, revealing he craves power (to the extent that the look in his eyes reminds Soundwave of Megatron and gives him a measure of respect) and the idea of being the middleman boss to a planet of slaves, answering directly to Megatron is very tempting to him.
TRON: Legacy: The Administrative Program Jarvis will salute whoever looks to be in power. Finally, Clu has enough of Jarvis and casually de-rezzes him without breaking a stride.
An actual psychological disorder in the Zombie Apocalypse novel World War Z (written by Max Brooks, son of Mel); "quislings" are humans who have nervous breakdowns and begin behaving like zombies. Unfortunately for them, the genuine article can tell the difference...
They also may have aided in tons of confusion and urban legends about zombies amongst the survivors.
Any voluntary Controller from Animorphs, but Hedrick Chapman deserves a special mention. You know, being the one who paraded Loren before the Yeerks and basically said, "Hey, lookit this! I gotta planet of six billion just waitin' for ya!" and all. Elfangor, Loren and the Yeerk he was trying to help, Sub-visser Thirty-two, all leave him to be sucked into a black hole. However, the Ellimist saved him and wiped his memory. When the Yeerks finally make it to Earth, he and his wife are infested, but only cooperate to keep their daughter, Melissa, free and uninfested. He becomes a Middle Management Mook and the Animorphs' go-to guy when they need someone to threaten or torture. Ahh, karma.
There's also Taylor, a former Alpha Bitch who lost her looks and her popularity in a fire. Desperate to regain the life she had, Taylor agrees to become a voluntary Controller in exchange for the Yeerks using their advanced technology to make her a Cyborg and restore her beauty. Unfortunately for Taylor, the Yeerk chosen to infest her is not exactly a pillar of mental stability...
David could be considered a subversion, as he threatens to betray the team to the Yeerks on a few occasions but never actually does it. It's heavily implied he's bluffing and hates the Yeerks as much as the Animorphs do.
And from VISSER there's Rich Huntley, the first voluntary Human-Controller. Edriss kills him for his trouble.
Severus Snape appears to be this, controlling Hogwarts on the behalf of the Death Eaters. Subverted when he was revealed to be a reverse mole.
Pius Thicknesse controls the Department of Magical Law Enforcement, and after Rufus Scrimgeour's, death the entire Minstrey of Magic. In the books this is the result of Mind Control, but in the movies it is implied to be voluntary.
Dolores Umbridge does not have any official ties with Voldemort, but she gleefuly uses her post to enforce his Fantastic Racism by running a Kangaroo Court to give Muggle-borns a choice between surrendering their wands and a Fate Worse Than Death. (Word Of God claims this earned her a life sentence in Azkaban after Voldemort's defeat.)
Shift the Ape, from the final book in the Narnia series, fits the above description perfectly.
In Kurt Vonnegut's Mother Night the American protagonist is asked to become The Quisling for the Nazis by an American agent to pass information to America. The book is about what being a collaborator does to his soul (and life), even though he knows he is doing it for a good cause.
The Ganymede Takeover, a 1967 science fiction novel by Philip K. Dick and Ray Nelson, has several such characters (as the alien invaders know this is the only effective way they can rule Earth), racist landowner Gus Swenesgard being the best example. Subverted in that when the aliens are finally defeated, the resistance set up Swenesgard to be their puppet ruler until democracy is restored. That is, if they ever intend to restore democracy...
In E. E. Knight's Vampire Earth novels, Quisling is a term often used to refer to Humans under Kurian rule.
The Diamonds, Spades, and Clubs in The Looking Glass Wars were loyal to Redd as soon as she took over. When Alyss resumes power, they switch loyalties again, and unfortunately weren't punished. This is rectified in the sequel, Seeing Redd. Jack of Diamonds is seen to have been imprisoned for treason. He does manage to escape and tries to join up with Queen Redd. This time, he quickly outlives his usefulness.
In Robert Silverberg's The Alien Years, a nerdy hacker breaks into the conquering aliens' computer system, but instead of trying to use it against them, he offers them his help in return for power and a harem.
Senator Viqi Shesh from the New Jedi Order willing works with the Yuuzhan Vong invasion, though it would be a stretch to say she was loyal to them her first loyalty was always to herself- she merely wanted to ensure her survival and position by teaming up with what looked like the winning side). This came back to bite her in the end, as the Vong, horrible as they were, actually had a rather strict code of conduct and found an obviously self-serving traitor repellant. Shesh found herself constantly scrambling to keep herself indispensible to the Warmaster lest she be unceremoniously killed off.
Most of the Peace Brigade members, they collaborate with the Yuuzhan Vong by handing over high ranking officials, and Jedi. But to the Vong, the term peace is synonymous for submission, as they already plan on enslaving the Peace Brigade when they win the war.
In Taylor Caldwell's early-1950's novel, The Devil's Advocate, the senior administrator of the Eastern Seaboard in a Communist-ruled America was secretly the head of La Résistance. He makes a Heroic Sacrifice at the end of the book, allowing himself to be assassinated so as to provide the scapegoat and poster boy for the downfallen dictatorship for Americans after the Second Revolution.
Lord Pryderi, in the final installment of the Prydain Chronicles, has always been a loyal ally of Prince Gwydion...only to show up for the council of war and declare that the only sane option is to join the enemy. Which he does. He gets Rewarded as a Traitor Deserves when, on Arawn's orders, he attempts to invade Caer Dallben and the place itself destroys him.
A few positive examples in A Song of Ice and Fire; when Daenarys starts conquering/liberating cities founded on slavery, she unsurprisingly gets quite a few people (whether ex-slaves or freemen with a conscience,) who fully support her regime, with a few particularly useful ones joining her council. Equally unsurprisingly, these people are viewed as quislings by the deposed masters, and many acts of murder and sabotage are carried out by the latter, who consider themselves La Résistance.
There's Gaius Baltar, who continued his role as President of the Colonies after the Cylons invaded New Caprica and wilfully collaborated with them throughout the subsequent occupation. Considering his character he most likely did this simply out of self-interest, although at one point he did literally have a gun pointed at his head when he refused to sign off on an order for mass executions of civilians. Went through a Karma Houdini when the revolution ended by joining the Cylon Fleet, but fate eventually caught up to him when he was later re-captured by the Colonials on another planet. After interrogation he was then put on trial for treason and mass-murder (although, ironically, not for his role in the first Cylon genocide). And acquitted, the Magnificent Bastard!
Felix Gaeta continued to serve as Baltar's presidential aide even after the Cylons arrived, in order to act as a Reverse Mole. Not even La Résistance, who knew they had a mole, know he was it. Gaeta came very close to being killed by a barely-technically-legal Kangaroo Court until the truth about his past was revealed at the last second. (He didn't even try to explain.)
In preparation for the imminent Rapture, Colbert advertised (on his show) shirts reading "Welcome Jesus!" And just in case, the other side of the shirt reads "Welcome 12th Imam!"
At the end of a commercial break, he expressed his hopes that the audience members at home were still alive and had not been slaughtered by a psychotic murderer lurking right behind them. But just in case, "Welcome murderers!"
After the Phoenix lander touched down on Mars, Colbert became worried about enslavement by Martian microbes, and dedicated a segment to ingratiating himself to them, just in case. "Martian microbes, remember who your friends are."
Councilor Na'Far from Babylon 5 is a highly reluctant example of this trope, being the figurehead for the Narn puppet regime after the Centauri conquers them. He believes that by willingly cooperating with the invaders he may be able to stifle some of the worst abuses of his people.
And Londo ends up being an incredibly rare completely sympathetic example of the trope, as his hellish years ruling the Centauri as a puppet for the Drakh are played as a totally unambiguous Heroic Sacrifice and an atonement for the crimes in which he was previously complicit.
Captain Lochley is a softer version, revealed to have been a Clark loyalist during the Earth civil war. However, she cited her duty to Earthforce rather than any seeking of power.
Quark in Star Trek: Deep Space Nine is extremely opportunistic, even for a Ferengi, and willing to run his bar under whomever is currently in control of the station. As the owner of the largest business of the station, he is somewhat of a spokesperson for the local store and restaurant owners. Knowing that, Sisko uses a combination of bribes and blackmail every time Quark threatens to leave the station. In the episode in which Bajor joins the Federation, he ceremoniously unrolls a banner in his bar, but it turns out to be the one of the Klingon Empire, which had been conquering several nearby systems some months earlier. He immediately runs to get the Federation banner from behind the bar, without even trying to cover up the mix-up.
Subverted when the Dominion takes over the station. He isn't so cheerful but keeps his head down. However, his brother is a member of La Résistance, and when they are all locked up he helps bust them out of jail.
Quark is a citizen of an outside power that is normally neutral anyway. It isn't clear that the term "quisling" would apply to him, especially as the main thing he does is keep a bar. He ran his bar when the Cardassians were in charge, when the Federation took over, during the Dominion occupation and then again when the Federation came back. In fact, he played a critical role in helping the Federation retake the station. His sole concern was that the Jem'Hadar weren't interested in anything he was selling (alcohol, food or holographic sex), pinning his hopes on the Vorta being 'alcoholic, gluttonous sex maniacs'.
More conventionally, Legate Broca, a last-minute replacement for Damar after the latter vacates the position by forming La Résistance, is completely loyal to the Dominion, even in spite of the Cardassian people rising up against the Dominion and having their cities destroyed because of it. Both Weyoun and the female Changeling treat him with nothing but contempt, and he is unceremoniously executed when they decide to preempt any potential Heel Face Turn on his part.
One Sliders episode has its own word for this: Thatchers. Apparently a version of Margaret Thatcher "welcomed its new Kromag overlords", and when they were driven out, the word for collaborators was inspired from her name (similar to this trope, probably because it also sounds much like "traitor/treachery" in English). The moral struggles of a "Thatcher" is a plot point of the episode in question.
The Castellan in the Doctor Who serial "The Invasion of Time" gets the chance to serve as Quisling to three despots; firstly the Doctor (when it seems that he's gone mad with power and taken over Gallifrey, then the Vardans (when they invade, seemingly with the Doctor's collaboration) and then the Sontarans (when the Doctor, having tricked the Vardans into thinking he was a collaborator, deals with them only to discover that the Sontarans were manipulating the Vardans).
In "Rise of the Cybermen," Rose Tyler's alternate universe dad is a high ranking official in Lumic's company. He saves himself from the resistance when he reveals that he was the one sending them information on the Cybermen.
The Controller in "Day of the Daleks" is explicitly called a Quisling by the Doctor in reference to his collaboration with the Daleks.
Later in "The Daleks' Master Plan" there is Mavic Chen, Guardian of the Solar System, who plots with the Daleks and delegates from the Outer Galaxies to take over Earth, while planning to betray the Daleks and take control of the Universe. He is Rewarded as a Traitor Deserves by the Daleks, who seem to have been plotting against all their allies.
Star Trek: The Next Generation had the Klingon house of Duras regularly collaborating with Romulans. Their father, Ja'rod, gave them access codes for their surprise attack on Khitomer, and years later, Duras pinned the blame on Worf's father, Mogh. Duras's sisters, Lursa and B'etor had Romulan Commander Sela supply their side during the Klingon Civil War in "Redemption".
In Secret Army, the staff of the Cafe Candide pretend to be this. Actually, they're members of La Résistance group Lifeline.
Farscape has a number of examples, especially Zhaan's unnamed lover, who she murdered when he became a Quisling for the Peacekeepers, and Volmae in "Thank God It's Friday... Again", again for the Peacekeepers.
Ro in the Blake's 7 episode "Horizon". He learns better.
House accuses Cuddy of being this for Vogler in Season 1, even name-dropping the original. Vogler buys his way into the hospital board's chair with a $100,000,000 donation, and when he starts using his position for ethically questionable practices, the board (and Cuddy) adopt a policy of appeasement so as not to lose the money. Cuddy eventually comes around when Vogler starts firing board members for voting against his motions.
And this is law, I will maintain Unto my Dying Day, Sir. That whatsoever King may reign, I will be the Vicar of Bray, Sir!
Bill Bailey notes in his song "Insect Nation" that crabs will be the "sideways Quislings" during the inevitable Bug War, joining with the insects despite not being insects. He also adds that the spiders will also side with the insects even though they're not insects either.
In the Paizo Pathfinder campaign, "Rise of the Runelords," Mokmurian, leader of the giants was this to Karzoug as giants were viewed as slaves in ancient Thassilon, not as generals or lords of some sort. This doesn't stop him from doing his level best to wipe out humanity so Karzoug can have lots of souls.
Pretty much how Chaos cults starts on any world in Warhammer 40000. Each Chaos God promises power in return for loyalty and worship, although the power they grant you is often at a high cost, and most don't survive it. This is why the Inquisition works so hard to root out chaos, since there's always one guy who'd want the Dark God's more tangible gifts (as compared to the less pleasant Imperial faith).
Also, Gue'vasa is the Tau name for humans who have turned their back on the Imperium of Man to serve the Tau Empire. They are mostly the descendants of Imperial Guardsmen who were abandoned in Tau territory after the Damocles Crusade, but occasionally, Imperial border worlds will rebel against Imperial control and secede to the expanding Tau Empire. This is used in meta to justify skirmish battles between the two factions, as they fight over control over the worlds; the Taros Campaign is a prominent example of this.
Note that Harmonia had conquered Franz's village before he was even born, and actually had a specific system in place for conquered groups to achieve the kind of elevation in status Franz hoped to achieve for his village if they proved themselves useful enough. And in the end, there's a good chance he succeeded, since by switching to the heroes' side he helped Sasarai regain his position as second in command of Harmonia and stopped Luc's destructive plans.
Suikoden IV has Snowe Vingerhut and his father. Snowe is portrayed as somewhat more sympathetic, as he negotiates for Razril to be occupied rather than risk a war with forces capable of blowing up an island, and is unaware of just how bad the occupation is thanks to be distracted by a false position. His father, on the other hand, is a straight-up Dirty Coward who ignores the atrocities committed by the occupying forces and stays holed up in his mansion.
Suikoden V has Lord De Beers of Leclar, who supported whoever happened to have the most power in the Senate at any given moment. During the Falenan Civil War, he ditches his post at Leclar to hide in the fortress town of Doraat, then leaves there once the Loyalist Army approaches to cower in Stormfist. Eventually, when the Loyalist Army approaches again, he flees the country altogether. Notably, both sides of the conflict regard him with scorn and dismiss him as unimportant.
Doctor Wallace Breen in Half-Life 2, though the Seven Hour War was an extremely bloody affair. Somehow, he managed to negotiate the surrender on the behalf of the United Nations and was appointed as the ruler of Earth. This is on top of undertaking the extremely dangerous experiment with a pure sample and ramping the equipment up beyond normal safe levels, causing the Black Mesa Incident. Then Gordon showed up again.
What's more, he seems to think he's he's helping humanity. It's not clear if things would be worse without him, though.
Marquis Ondore from Final Fantasy XII. Technically a subversion because his ruling fief isn't actually Archadian territory, as it remains neutral, but Ondore is infamously known for being pro-Archadian. On the other hand, however, he extensively funds resistance groups across Ivalice against the empire in a dangerous double-game, which turns into all-out war when another empire exploits the situation.
What about Basch's brother Noah, better known by his title Judge Gabranth?
Wouldn't Vossler count as well while being a little bit of a variation, since he actually sells out the party to the Archadians on the premise of Princess Ashe becoming a puppet queen until Larsa took over and then having the two work together to free Dalmasca? And then once things go to hell on the Leviathan, he's killed in the explosion? The funny thing is that plan of his would've probably worked, eventually
There is also the Dirty Coward Count Borghen from Final Fantasy II. He allowed the Palamecians to overtake Fynn, is held in contempt by said Palamecians, ultimately an inept foe, but acts as the game's first major antagonist and even manages to kill Josef.
Fehn Digler (not to be confused with Heartwarming OrphanFehn), the newscaster in Beyond Good And Evil, is a helpless suck-up to the Alpha Sections. He even has a personal contingent of Alpha guards! At the end of the game, when the Alphas are on their last legs, he switches sides suddenly, to no one's surprise.
Saren Arterius in Mass Effect, who honestly believes the invasion of the Reapers is inevitable and that helping them take over the Galaxy will prevent pointless sacrifices.
Of course, there's a bit of Mind Control involved there, but it was never made clear exactly where Saren's interests ended and Sovereign's began.
Also, Quisling is mentioned by name in comparison to Ashley's grandfather, who surrendered his colony to an alien army rather than see millions of civilians die in a pointless Last Stand. It's rather clear that he was a scapegoat, but the incident prevents his granddaughter from rising higher in the ranks than a glorified security guard, until Captain Anderson takes her on board the Normandy.
Given how young she became a Gunnery Sergeant, and by Mass Effect 3, a Second-Lieutenant, she seems to have gotten past this.
In Mass Effect 3, Councillor Donnel Udina decides to stage a coup at the Citadel with the aid of Cerberus, and have all his fellow Councillors assassinated. His motivations are left deliberately ambigious; Indoctrination, ambition, fear, and frustration at his fellow councilors' refusal to help the people of Earth, all are discussed as possible options.
Another BioWare example is Chuundar from Knights of the Old Republic. So long as he remains High Chieftain, he's all too glad to sell his own people to Czerka, arrange for his brother's exile and spread lies that his father has gone mad in order to get the party to do his dirty work.
In Mech Quest, Kingadent Slugwrath turns out to have been selling out the planet of Lore and Soluna City to the Shadowscythe, sabotaging the Soluna Defense Force and seeking to destroy their leader, Odessa Pureheart, and turning a blind eye to Sys-Zero's kidnapping and assimilation by the Shadowscythe. After you kick Slugwrath's ass in the final battle of the first chapter, he attempts to escape in the head of his mech, but runs out of fuel, crashes, and is overrun by Shadowscythe. He ends up as a still-living head in a jar on the desk of the head of EvilCorp, who looks very much like Zorbak, as he muses on how at least he got the immortality he'd always wanted.
Gul'dan, Blackhand and the other members of the Shadow Council in Rise Of The Horde and Warcraft: Orcs and Humans. Unlike the other orc leaders, who were tricked into making a pact with demons, they were aware of Kil'Jaeden's deceit and helped him transform the orcs into bloodthirsty monsters in exchange for (political and magical) power.
Dar'Khan Drathir in The Sunwell Trilogy. He's the one who betrayed his homeland Quel'Thalas by letting Arthas in and have his people slaughtered by the soon-to-be Lich King.
A small-time version of this can be found in Jacoby Drexelhand, Korthos villager turned Devourer cultist and Sahuagin collaborator in the introductory Korthos Island missions from Dungeons & Dragons Online. While most Korthos villagers who joined the Devourer cult were kidnapped and forcibly indoctrinated into it, Jacoby gave himself willingly to the Devourer. When you confront him during the instance "The Collaborator," he tells you that the Sahuagin will kill anyone who doesn't convert, and that he's just watching out for his own hide. You promptly prove him wrong by fighting off his allies, tracking him down, and sending him into Khyber's embrace.
Following Jacoby's death, his body is taken to the Decrepit Catacombs by the cultists of the Devourer and raised as an undead wight, who you then have to fight in the finale of the instance "Necromancer's Doom."
Lionwhyte in Brutal Legend sells humanity into slavery to Doviculus, and chews out Ironheade for not seeing how much better off they are under his rule.
Either Papa Khan or Regis could qualify in Fallout New Vegas. Papa Khan is so keen for vengeance against the NCR that he's willing to enter into an alliance with The Legion, despite their practice of backstabbing every tribe who sides with them, press-ganging all the worthy men into their military and enslaving or killing the rest. Regis will take control of the Great Khans if Papa is assassinated, and will agree to a truce with the NCR in order to aid them against the Legion. Papa Khan however can be convinced to break off the alliance if you convince enough of his advisers to speak out against him and disgrace the frumentarii in their camp.
It's also justified in Papa Khan's case in that the Legion sent a Frumentarii to act as an ambassador, in other words feeding a ton of bullshit to the Khans (including telling a female Khan about how awesome it'll be for her to be a Legionnaire, despite the fact that the Legion's treatment of women is nothing short of inhumane), with only Regis being totally unconvinced and the rest are either just eager for vengeance or simply apathetic.
In EarthBound, Pokey joins Giygas fairly early in the game, and acts as a thorn in Ness's side for the first half of the game. He spends most of the rest of the game on the run, until he finally shows up in the endgame as Giygas's Dragon. After Giygas's defeat, he manages to escape and becomes the Big Bad of Mother3.
Captain Vole from Girl Genius is a Jagerkin example of this trope; the only one of their kind to utterly discard his loyalty to the Heterodynes to serve Baron Wulfenbach, Vole doesn't consider himself a Jager and seems to relish the idea of destroying what is left of the Heterodynes so the Jagers have no choice but to follow his lead. Because of the friction this causes with the other Jagers (who all serve Wulfenbach while awaiting the Heterodynes' return), Vole has been forcibly assigned to Mechanicsburg — the only town in Europa the Jagerkin cannot enter.
See also Doctor Silas Merlot. When Dr. Beetle is killed, Merlot attempts to pose the suggestion to Baron Wulfenbach that no one need know that the well-respected Beetle is kaputski. Unfortunately, the Baron is a little smarter and a bit more principled than most overlords; he despises traitors, and not just because a man willing to change sides that easily certainly can't be trusted to stay loyal to you. Merlot's punishment? He has to run Beetleburg, after the populace has been made aware that Dr. Beetle's death was the direct result of Merlot's petulant theatrics. He doesn't learn, either.
Tsukiko the necromancer in The Order of the Stick, who joins the Azurite military solely so she can switch sides and help Xykon at the first opportunity.
And a couple other prisoners the Paladins released. In retrospect, that was pretty much a universally bad decision on their part, as the prisoners seem to all be Chaotic Evil and immediately started looking for ways to join Xykon. Yes, folks, in Dungeons & Dragons, being the Quisling can be a major part of your morality and/or religion!
Only Tsukiko joined Xykon. One of the prisoners chose to remain in prison in the hopes of defecting after the goblins won, and the other betrayed Azure city not to Xykon but to Daimyo Kubota. Speaking of which Daimyo Kubota, who goes so far as to try and assassinate his lord in the middle of an invasion.
And it turns out Gamzee actually is this. He's the only character who hasn't been tricked into following Doc Scratch's plans. (Rose did work with Scratch, but she had no idea what his true plan for her was.)
Numerous celebrities become this on Post-Scratch Earth, most notably Insane Clown Posse and Guy Fieri.
In Vattu, the title character encounters another slave who reveres the Sahtan civilization and scorns the fluters that he came from.
In article about a computer learning to play "pong" from EGMi, EGM's digital magazine, the writer of the article said, "I'd like to be the first to welcome our new computer overlords as that's how a lot of apocalyptic science-fiction novels start."
Journalist Amanda Connor becomes the face of the Neosapien occupation in Exo Squad, much to the disgust (but not surprise) of her ex-husband, Sean Napier, himself leader of La Résistance.
Also in Exo Squad, after Phaeton takes over Earth, Venus, and Mars, the mayor of Chicago Phaeton City is giving speeches welcoming their new masters practically before the smoke has cleared.
Kent Brockman, when believing the world was about to be invaded by a master race of giant ants, comments that "I, for one, welcome our new insect overlords. I'd like to remind them that as a trusted TV reporter, I can be useful in rounding up others to toil in their underground sugar caves." Once this is all cleared up, he says, "Well, this reporter was... possibly a little hasty earlier and would like to... reaffirm his allegiance to this country and its human president. May not be perfect, but it's still the best government we have. For now." The camera pulls back to reveal a hastily-drawn "HAIL ANTS" poster which Kent quickly rips off.
He does it again in "The Joy of Sect", this time for his job:
Kent Brockman: Springfield has been overrun by a strange and almost certainly evil sect, calling themselves "the Movementarians". In exchange for your home and all your money, the Leader of this way out and.. wrong religion, claims he'll take believers away on his spaceship to the planet "Blisstonia." Excuse my editorial laugh. (laughs) But— (a note is passed to him) Ladies and gentlemen, I just learned of a change in this station's management! Welcome, Movementarians! Continue to improve our lives! I love you, perfect Leader...and new CEO of KBBL broadcasting!
Mr. Burns in The Simpsons has been heavily suggested to have been aiding the Germans throughout the World Wars and, unlike Schindler, takes pride in having built bombs that worked, dammit!
Wuya from Xiaolin Showdown. Once one of the most powerful evil forces in the world, she is condemned to exist in spirit form and needs solid people to do her dirty work for her. She usually works for/with Jack Spicer, the incompetent junior villain who freed her from her puzzle box, but the series made a Running Gag of her going off to work with villains she saw as more powerful, only to come crawling back to Jack as soon as those villains were defeated.
Vidkun Quisling, the real life Trope Namer, was a Norwegian fascist politician. Nazi Germany invaded Norway on April 9th 1940, and hoping for an easy capitulation like Denmark the day previous, asked Quisling to form his own government. Quisling attempted to do so, only to find he had no popular support and no one listened to him. The Germans attempted to negotiate support for him with the Monarch of Norway and the government in exile, but were flatly refused. He was finally appointed Minister President of Norway in 1942. When Germany lost the war, he was accused of high treason and sentenced to death by firing squad. A Political Cartoon reveals that Norwegians were using "quisling" to mean "traitor" as early as 1944. Winston Churchill used the term in speeches from 1940 onwards.
The Germans didn't actually ask him to form a government at first. Quisling announced the formation of his (first) government over the radio on the very day of the invasion, before the Germans had time to do anything about it. Six days later the Supreme Court dismissed his government and replaced it with an "administrative council", which pledged allegiance to Germany. Reichskommisar Josef Terboven then replaced this council with a handpicked puppet government, of which Quisling was not a member (although several members of his party were), a few months later. Terboven explicitly did not want to allow Quisling to form a real government, since he believed that would only antagonize Norwegians further. The Reichskommisar also thought Quisling was a feckless moron, but couldn't exclude him completely, since Hitler apparently liked Quisling. Finally, Quisling was allowed to form his own government in 1942, but his authority was limited to areas of policy were German interests were not at stake.
Quisling was an educated officer, who formed his own right wing party (National Samling, or NS) in 1933. Before the war, he got some support from the righters and the farmers because of his actions during the Great Depression, but lost support when times improved up to the war in 1939. Because of his connections to the other fascist movements, he was aware of German plans early on, and because some 20% of Norwegian high ranking officers was in his party, he gambled on them to step down when the Germans invaded. Many of them actually did. This interference left the Norwegian mobilization in total disarray, with a couple of towns being given over without any gunshots at all. No wonder he was labelled traitor. It gets better when considering the aftermath of the war in Norway: History went far in blaming the massive confusion on the actual government. In spite of the fact that Quisling himself was executed.
Before he became a Nazi collaborator, he was - with much Irony in Hindsight - a humanitarian, having worked in Ukraine to help solve their hunger in 1922, and in Armenia, to help with the population transfers. In fact, he was the only one worker on both endeavours to be singled out and praised by his boss, Fridtjof Nansen.
The United States has its own "Quisling" in the form of Benedict Arnold, whose name has become synonymous with "traitor" in American English. As a general in the rebel American army, Arnold performed a number of particularly courageous acts, but a combination of financial troubles and a perceived lack of recognition by his peers coerced him to sell out his comrades to the British. He tried to take a fort (West Point, today the site of the US Military Academy) with him, but his plot failed and he ultimately fled back to Britain. Recent scholarship suggests that Arnold's wife Peggy Shippen Arnold might have instigated the betrayal, though at the time she was cleared of charges.
Wang Jingwei, one-time heir to Sun Yat-Sen until Chiang Kai-Shek asserted himself as the leader of the GMD with the backing of the military. In 1940 he became President of the Wang Jingwei regime based out of the Japanese-occupied areas of China. His name is considered a byword for supreme treachery to a degree that makes Benedict Arnold's look petty. Fortunately for him he died of natural causes in '44, though his wife was tried and found guilty of treason at the post-war Nanjing War Crimes trial. To be fair, Wang had good cause to believe that his defection could ensure that the relationship between China and Japan would be one of co-operation, and not exploitation. However, the political situation changed as Japan moved to strike out at the Allies and the USA, and he quickly became little more than a puppet. All he could really do from then on was try to limit the worst excesses of the Japanese Army as they pretty much bled the country dry.
Puyi, the "emperor" of Nipponese-occupied Manchuria ("Manchukuo", they called it). He didn't much care for the job and found himself constantly arguing with the Japanese and their exploitative zaibatsu corporations; the only reason he took it on was that the Japanese wanted a monarchist Quisling to rule the northeast, and he happened to be the only candidate for the job (having previously been the legitimate Qing Dynasty Emperor of China before the Xinhai Revolution).
Pierre Laval, who was The Man Behind the Man to Marshal Pétain in the Vichy French regime, and pretty much the reason "Les Collaborateurs" is a French phrase. When France was freed from Nazi rule, both were sentenced to death, though Pétain got his sentence commuted to a life sentence by De Gaulle.
For the WWII French in general, before the fall of the Third Republic a slogan for French Quislings was "Better Hitler than Blum" (Blum was the Jewish French Prime minister).
One of Ancient Rome's favored tactics for conquest was to promise a local chieftain that he will be able to rule as a petty king over the conquered land if he agrees to provide information or troops to the Romans. What made it particularly effective was that the Romans punctiliously kept their word; submit, and Roman armies would protect you from others; don't submit, and the results would be very messy and very bad for you.
The Romans also created cultural quislings where they would demand the pliant chieftains' sons as "hostages" and ship them to Rome, where they would be treated to the high life and the best Roman culture can give. This resulted in the heirs becoming thoroughly Romanized and converting a previously "barbarian" kingdom to little Rome.
Ephialtes of Trachis is remembered in Greece in the same way that Quisling is in Norway, and "Ephialtes" has become a synonym for traitor. He betrayed his countrymen and joined the Persians during the Battle of Thermopylae, showing them a mountain path that allowed the Persian forces to outflank the Spartan and other Greek forces that were defending the narrow pass.
After the American Civil War, the formerly little-used term "scalawag" (meaning "scoundrel") became widely-known as a term of abuse for Southerners allied with the North during the war and Reconstruction.
The equivalent term in South Asia (or at least in the Bengal region) is 'Mir Jafar'. Mir Jafar was a courtier and a general in the court of the Nawab of Bengal, Sirajuddowla. He made a pact with Robert Clive of the East India Company and during the historical Battle of Plassey, stood by and did nothing while Sirajuddowla's army was slaughtered by the British Army. This treachery thus led to the beginning of the Company's political domination of India and eventually to the British Raj and 200 years of political, economic and social domination.