Char Aznable of Mobile Suit Gundam. Bonus points in the first series for being re-hired by the very government he betrayed and deserted.
Char states at the end of Zeta Gundam that he'll leave his ambitions of escorting mankind to space to the AEUG. In the years that follow, however, he gets tired of waiting around, culminating in Mobile Suit Gundam Chars Counterattack. He was forced into leaving AEUG, after faking his death after losing to Haman. He was never really comfortable in the AEUG anyway, and being presumed dead helped him get out of his obligations. It's not really treason so much as not renewing his contract for another term.
A Playstation 1-era Zeta Gundam game offered a bit more elaboration in Quattro's storyline, showing that Kamille's getting mindraped was the tipping point, since he wanted to entrust the future to Kamille's generation.
Gundam 00 - Ribbons!. Alejandro Corner, Wang Liu Mei, and Regene Regetta are also not very trustworthy people. Their betrayals are often of each other.
After War Gundam X - The Frost Brothers betray from their initial debut up until the final episode, killing basically everyone who either employed them or worked for them.
Code Geass - Suzaku Kururugi. Bismark, the Knight of One, even lampshades the trope by openly stating that he betrays everyone and everything, and they expected him to do that. Which isn't really all that inaccurate since he was helping with a coup d'etat at the time. Suzaku killed the leader of his countrythree times, having some kind of special relationship with the killed leader in all three cases. Granted, one of these cases wasn't an actual betrayal per se, but he'd betrayed that person earlier on. For the record, the first of the three leaders who Suzaku killed was his father. Even Suzaku openly admits to being this way in an earlier episode:
Suzaku: I told you before, Lelouch...that I was going to change this world from the inside. Lelouch: Even if it means selling out your friends?! Suzaku: That's right.
There's also Diethard Reid, who first worked for the Britannian empire, then became a Black Knight, and then joined Schneizel purely because of the thrill.
Villetta Nu. You know, the woman who first fought for Britannia, then lost her memories and fell in love with a rebel, then regained them and shot him, then was blackmailed into fighting for the rebels, then betrayed her blackmailer to his eventually undyingly loyal knight, then reported this to her blackmailer, then betrayed him and joined his sibling who was trying to kill him, then ended up on the side of the guy she fell in love with and shot, and eventually had a baby with him? Her.
Nergal of Martian Successor Nadesico as a whole, and especially their chairperson Nagare Akatsuki have no trouble whatsoever constantly backstabbing The Government and their employees, only to come sidling back to either or both when things don't go their way. One suspects said "chairman may just be doing it for laughs".
By the same token, the leader of the Alien Invasion has no qualms about having his underlings covertly assassinated, or with starting a new faction and backstabbing everybody when his invasion plans don't work out.
Neon Genesis Evangelion has a few examples. End of Evangelion kicks off with Gendo and the SEELE committee simultaneously betraying each other and every single other faction in the series. On the other hand, Ryoji Kaji is simultaneously double-crossing SEELE, NERV, and the Japanese government all in a personal quest to figure out what the fuck is going on, and he turns out to be one of the more unambiguously heroic characters on the show. He doesn't get away with it, though.
Slayers - Xellos is a pretty good example of this trope, as his loyalties can (And will) change at the drop of a hat (except for Zelas Metallium, the mazoku lord he serves). In the books, the sheer awesomeness of this is turned up to eleven. Mazoku are bound, absolutely, to follow the orders of their superiors. He still manages to betray them. In the anime, it comes off as Xellos just having fun with humans by frusterating them.
Zelgadis also suffered from a minor case of CBD very early on in the series, although it was to a much lesser extent.
The Tower of Druaga: Neeba, older half-brother to protagonist Jil, has a bad case of this. This guy betrayed Jil and his own adventuring party twice and also betrayed the party who took him in and trained him in his Magic Bowman class.
In Weiss Kreuz, Schwarz inevitably turn on every single one of their employers over the course of the multi-part series.
One Piece has a scene where the Straw Hats are told not to trust one of their True Companions, Nico Robin, as every organization she has ever joined was destroyed before her departure. Unlike Usopp's "Chronic I-Must-Not-Travel-To-This-Island Disease," her disorder is presumed cured. When her backstory is revealed, we learn that she actually suffered from Chronic Getting-Backstabbed Disorder, since the age of 8 no less.
Blackbeard on the other hand plays this straight. He betrayed Whitebeard, killed one of his own crewmates, and later captured Ace to deliver him to the World Government so that he could join the Seven Warlords of the Sea. When the Warlords are later recalled to Marine Headquarters to defend it from Whitebeard's expected attack in retaliation for Ace's capture, Blackbeard then betrays them by heading for Impel Down instead in order to free some of the world's most notorious criminals and recruit them into his crew. His motivation for these betrayals, and indeed for everything he does, is to fulfill his dream of becoming the Pirate King.
Nami at the beginning of the series when she betrayed Luffy to Buggy, then she betrays Buggy himself to join up with Luffy again. Then just before Sanji joins the crew she steals their ship and their treasure for Arlong. Then she betrays Arlong and goes back to Luffy again. They even lampshade these betrayals in the sixth movie when Nami accuses Usopp of betraying her and he says that that's her thing.
Sasuke from Naruto changes allegiances/betrays people so often and for so little reason that it's a wonder anyone trusts him anymore. In order, he betrayed the Leaf Village (along with a personal betrayal of both his teammates); Orochimaru; Itachi's beliefs; Akatsuki; Jugo and Suigetsu; Karin; Sakura (again); and White Zetsu. Some of his betrayals are reasonable, but most go along the lines of "if I stay loyal, I don't get anything out of it". Tobi seems to have noticed this trend and beat him to the punch by promising to hand him over to Kabuto.
Kabuto is a chronic backstabber himself, having betrayed Konoha and Akatsuki , although he subverted the trope with Orochimaru. Unsurprisingly, Madara doesn't trust him. And with good reason, as Kabuto is planning on getting the powers of Rikudo Sennin himself, and is more concerned with making the Alliance and Madara's forces destroy each other.
While Kabuto did remain completely loyal to Orochimaru, at one point Orochimaru was uncertain whether this was the case. He didn't mind, though. Instead, he just thought it'd be amusing to watch and see whether Kabuto betrayed him like he does everyone else.
From Robotech/Macross, we get Khyron/Kvamzin Kravshera. Known by his own people as "Kamjin the Ally-Killer". It's not a reference to his battle tactics. It is a reference to the fact that he'll murder his own men, and other people's men, to advance his own objectives or if they displease him in some way. It's only the fact that Britai and Laplamiz have vastly superior firepower and numbers to Kamjin that prevents him from launching a full-on mutiny.
Sora in .hack//SIGN, who is very clearly not to be trusted. However, he's one of the strongest characters in The World and has a good ear for rumors. By the end, he's killed BT three times, switched to and from her side about as many times, worked with the Crimson Knights and finally ends up accidentally buying time for Tsukasa and Subaru to escape. He wasn't expecting to get caught, but eh, at least he tried at the end. He stops his backstabbing ways after he loses his memory and returns as Haseo
In Outlaw Star, Professor Gwen Khan has a bad habit of using people to achieve his ultimate goal and acquire the power of the Galactic Leyline, and then ditching them once they've gotten him as far as they can. In the course of the series, he's rode on the coattails of the Kei Pirates, Gene Starwind and his crew, and finally the McDougall brothers, always skipping off when they've done all they can for him (although Gene manages to pull a premature backstab on him first). He also manipulates the android Melfina, who he created himself, as a bargaining chip, but unlike most examples of this trope doesn't seem sinister for it, mainly because he seems more True Neutral then Neutral Evil.
RG Veda: Shashi — better known as Ashura's mother. After the Ashura clan grants her a god's lifespan as their priestess, she promptly swears off those lowly, miserable humans (that she used to be one of). Then, she seduces Lord Ashura so that she can rise in status as his wife. Still not satisfied, she gets pregnant with another, more ambitious god's child at the same time as Ashura's child (twin half-brothers), and betrays the entire Ashura clan (including her husband) to their deaths when Taishakuten (her other babydaddy) revolts to become the new Emperor.
And when Ashura was born, she tried to kill her as well, because a child of Lord Ashura was no longer advantageous to her. After three hundred years as the wife of the iron-fisted emperor of the gods, is she through digging for more power? No! She plans to supplant him with her son and rule through him. Oh, Shashi, you backstabbing little minx, you!
Mine Fujiko in Lupin III betrays Lupin in most of her TV appearances and all of her movie appearances except The Castle of Cagliostro, and even that's arguable. Then,if it looks like the villain (and/or Inspector Zenigata) isn't going to keep their end of the deal or she can get a better deal with Lupin, she'll betray them as well. Despite this, Lupin continues to blindly trust her until the next betrayal. In one instances he even comments he is expecting her to betray him, but Lupin's weakness for Fujiko certainly does prevent him from becoming a Boring Invincible Hero.
Death Note's very own LightYagami qualifies. Over the course of the series, he betrays the trust of L, whom he considered, at least at one point, to be a friend (saying at one point, "Ryuuzaki is Light Yagami's friend, but L is Kira's enemy"). He also betrays his father and his co-workers, especially Matsuda, who genuinely looked up to him, by murdering or conspiring to murder them all. He betrays his fiancee MisaAmane by starting a relationship with KiyomiTakada — besides, you know, considering murdering her as well. He continues on to betray this girlfriend as well, killing her when she outlives her usefulness to him. He ALSO betrays his devoted heir TeruMikami at the Warehouse by denying that he knew him. Considering his betrayal of Naomi Misora's trust and his betrayal of his mother's and sister's trust (he considers killing them both at various points in the story), and the list only goes on. All in the name of a New World.
Though in his defense, he did all he could to make the situation so that it would be impossible for him to kill his family.
Michio Yuki from Osamu Tezuka's manga, MW, has betrayed everyone over the course of the manga. He killed a man who happens to be his client at that time. Afterwards, he starts a relationship with Miho, his corrupt boss's daughter, only to have her killed. Later on, he betrays his own boss, whom he trusted with his life, when it turns out that he's part of the MW cover up. He betrays Sumiko, whom she keeps falls in love despite how evil he is, by starting a relationship and marrying Mr. Nakata's daughter, only to betray her later on when she is told by Detective Meguro of his evil actions. Prior to that, he betrayed Father Garai, the man whom he formed a homosexual relationship with, by sending him to a nightclub to take a picture of him with a customer. He did all that to achieve his goal: obtaining the MW, the same gas that loses his morality, and use it to end the world when he dies.
In Digimon Xros Wars, DarkKnightmon revels in this trope, backstabbing everyone he allies with, even his brother.
Of course, his brother Bugramon, fully expected his betrayal. In fact, Bugramon was disappointed that when the time came, DarkKnightmon was not powerful enough to successfully defeat him.
Seemingly every last Drule/Galveston commander subordinate to Teles/Hazar in Vehicle Voltron / Dairugger XV basically waits for him to go off the viewscreen, sighs/laughs and orders the attack anyway, mocking his efforts for peace in the process. They all either die or 'barely get away in an escape pod', depending on the edit.
Delphinium in the "Blue Dragon" anime fits this rather well. She betrayed Salinas for no particular reason, even though he succeeded in completing his objective, turned on General Logi after he revolted against Gran Kingdom, betrayed the White Guardians by leaking information to Logi, and wasn't loyal to him either. Not to mention that Deathroy, the source of half her power, and the only ally that she never demonstrates any outright disloyalty to, orders her to kill all the members of the Legion of Elite Species. Guess what she doesn't do to Noi, Rotarus, and Hildegard (literally HALF the members of the legion) after the final battle.
Not only that, but none of her reasons for doing any of this are ever revealed. Her true motives and loyalties, if she even has any, are left completely unknown at the end of the series.
AND it gets so bad that the White Guardians even expect her to betray them when it comes to that, even formulating a plan assuming that it would happen, and using it to their advantage.
There's also Lien-Da. Let's see: first, she and her brother Kragok kill their father so that they can take over the Dark Legion (though Kragok then cut her out; guess this trope runs in the family). Years later, after the Legion's been reorganized into the Dark Egg Legion and being led by Lien-Da's distant ancestor Dimitri, she eventually destroys his life support system and leaves him for dead so that she can take over. And then, a few issues after that, she tries to betray the current Big Bad, the Iron Queen, and become the Dragon Ascendant... it doesn't go well for her.
Nack the Weasel also qualifies: He often sells out his comrades to either save his own skin or because they are a hindrance towards his mission. Usually, Sonic and his friends often get him to help them by hinting that they'll put him in jail with his friends (who from what is shown of them, most likely intend to exact revenge on Nack).
Gambit has switched sides so many times that it's a wonder that any team, let alone the X-Men, take him— although the fact that he's pretty consistent in choosing the side with Rogue on it probably allows whoever his current employers are some degree of peace of mind, if not exactly a high degree of long-term trust.
Mystique. In one issue, Cable (time traveling dude from the future) even mentioned that in his time, "Mystique" was used in much the same way that "Judas" is used now.
Mister Sinister betrayed Apocalypse immediately after being empowered by him, has betrayed him again in several alternate timelines, and knifed the High Evolutionary and Malice in the back as well.
Daken, Wolverine's son. In one issue, he faces Cyber (whom he was allied with in the past) and chooses to be on Wolverine's side. Then betrays W. and sides with C. because "C. has a better plan". Then comes out that there is no freakin' plan! Then betrays C. again and says he planned it all with W. from the start... and then he betrays W. too. And the X-Men, for good measure.
Every Astérix villain. The Romans at least, parodying the politics of the Roman Empire.
In Empowered Thugboy's former group, the Witless Minions' MO was this (mostly by swiping their stuff for money), though they're not above mind screwing an employer until they suffer a nervous breakdown. This ends BADLY when they made the mistake of trying to dupe Willy Pete.
In ABC Warriors, Blackblood's weapon of choice is listed as "treachery".
Raven from Teen Titans has a habit of being brainwashed or suddenly turning evil. When some new members join up, Starfire gives them a run-down on Raven's backstory, trying clearly to downplay the amount of times this has happened and emphasize her tragic life. The new members agree to secretly keep an eye on Raven, with Robin summing up, "She's betrayed them more times then they're willing to admit."
New Gods: Darkseid. Whenever they have to work together with him for the greater good, it's not a question of whether or not he's going to betray them... just when. Darkseid's right-hand-man Desaad is even worse. While most residents of Apokolips revere Darkseid fearfully, the sadistic Desaad dreams of betraying him and becoming ruler. He's smart enough to not try it until the opportune moment, but he still slips up enough for Darkseid to murder him repeatedly. Over and over and over.
Marvel's Loki does this at any given moment, and why his brother The Mighty Thor still gives him the time of day is anyone's guess. He knows it, too, and isn't always happy about it: Kid!Loki was created because his previous incarnation realised that his treacherous nature had made him too predictable - an unacceptable state for a God of Chaos.
He gets a taste of his own medicine whenever he teams up with Dormammu.
Marvel's Thanos isn't the most reliable guy to have on your side either.
Cheshire, former member of the Secret Six is very much this, but unfortunately for her The Society catch on and are not idiots.
Suffice it to say that bringing The Joker along on your evil plan du jour is not a sensible career move.
Played with in Infinite Crisis - Alex Luthor is Genre Savvy enough to leave the Joker out of his grand scheme, but does it ever come back to bite him in the end, especially when he's been defeated and the Joker's got him cornered in a dark alley...
Lex Luthor is Dangerously Genre Savvy enough to bring Joker into his villain team-ups without actually trusting him (or anyone else really). Lex knows it's better to let the Joker have his fun while pointing him in the general direction of his enemies. That and Lex actually likes Joker's sick sense of humor, finding him "strangely compelling company". Lex, on the other hand, doesn't fit this trope. He does occasionally honor his bargains, which makes the times he doesn't that much harder to expect.
Lulu Romanov in Nikolai Dante has a case of this. Unusually, when all is done, she ends up as one of the good guys.
During the Grazton arc of The Tainted Grimoire, Barley commits a series of betrayals. First was betraying a good guy to the bad guys, then betraying the bad guys to get help from other good guys to save the good guy he himself betrayed and finally, in a misguided attempt to make sure everyone comes out alive, betrayed the other good guys to the bad guys.
Eric Qualen of Cliffhangermight have actually pulled off his elaborate scheme if he had assembled a team of henchmen that actually liked and trusted each other.
Spy Kids - The real Big Bad, Mr. Alexander Minion made a business out of this. He was a Dragon for hire that always ended up betraying his master and hijacking their Evil Plans for his own purposes.
The Largo siblings from Repo! The Genetic Opera are vying for a place as their father's heir, and are pretty damn vicious about it.
Jack Sparrow from Pirates of the Caribbean; it rubs off on everyone else, too. Jack and his more-or-less friends betray each other constantly, yet always end up on the same side again in the end.
Star Wars - The Sith use betrayal and treachery as their modus operandi. If you're able to keep what you take, you deserved it. If the Master can't keep his subordinates in line, then he shouldn't be the Master. Palpatine gets Anakin to kill off Dooku, then later tries to get Luke to kill off Vader and become his newest apprentice. While at the same time, Vader tries to get Luke to kill off Palpatine so they can "rule the galaxy as father and son."
'Palpatine, as gatekeeper of the Telos Holocron': "Choose someone as successor and you will inevitably be succeeded. Choose someone hungrier and you will be devoured. Choose someone quicker and you won't dodge the blade at your back. Choose someone with more patience and you won't block the blade at your throat. Choose someone more devious and you'll hold the blade that kills you. Choose someone more clever and you'll never know your end. Despite these cautions, an apprentice is essential. A Master without an apprentice is a Master of nothing."
It was recently asked if there will be an opportunity for this sort of political backstabbing in the Inquisitor storyline. The response; "More than you can possibly imagine."
Ironically, Darth Sidious's own master, Darth Plagueis, attempted to avert the trope by having himself and Palpatine/Darth Sidious form a genuine bond. Unfortunately for him, Sidious still managed to do it onto him anyway.
General Hein of Final Fantasy The Spirits Within seems to inadvertently or otherwise kill off almost all of his allies within the course of the movie. The best example of this is when he tells his inferior to collect up "his most trusted troops". Within the next fifteen minutes, these troops are all dead due to Hein's poor judgment. Later, near the end of the film, he overrides the fail safes of the Zeus orbiting laser cannon, causing it to explode and killing everyone onboard, himself included.
Zombieland - Wichita and Little Rock. First, they fake a zombie bite on Little Rock as part of a scheme to steal Columbus and Tallahassee's weapons and vehicle. Then when the guys catch up to them, they hijack their new vehicle, holding them up with their own weapons. At least they let them come along this time, and eventually the group builds a grudging rapport. Next morning, however, they steal the truck again. Finally, after the guys they've repeatedly betrayed rescue them from certain, messy doom, they drive off again. They were joking this time, knowing that the guys would be all too willing to take them seriously.
The opening sequence of The Dark Knight has a long chain of henchmen backstabbing each other, with the Joker killing the final henchman.
At least the last one sees it coming. The Joker manages to avert the Mexican Standoff.
The Joker later reveals that he doesn't care one bit about money, and goes to show just how much he truly doesn't care about it by setting the half of the Mob's money that he earned by retrieving Lau on fire, meaning that the backstab was most likely instigated by the Joker solely for the laughs.
Ward Abbott from The Bourne Series is a fine example — he first betrayed his superiors to form a black ops squad with Conklin, then betrayed his black ops squad to use it for personal gain and finally betrayed Conklin as well.
Scar from The Lion King is a classic case of this. He has his own brother killed, tricks his own trusting nephew into blaming himself, tries to have that nephew killed, drives the hyenas (who helped him kill his brother) nearly to starvation, and then when confronted by his previously self-blaming nephew, (who finally saw Scar for the backstabber he was) Scar tried to blame everything on the hyenas to save his own hide. Even though all this lying and backstabbing is what got him into the situation he was in to begin with.
Simon Gruber in Die Hard With a Vengeance (played by Jeremy Irons, who voiced Scar). He betrays his Middle Eastern clients by stealing the gold they hired him to destroy and then screws over some of his accomplices to make sure he gets as large a share as possible. In the alternate ending, which takes place a few months after a successful heist, he has even eliminated his girlfriend to rob her.
Dr. Moriarty from Sherlock Holmes A Game Of Shadows. Besides eliminating many of his henchmen after they serve his purpose (Doctor Hoffmanstahl, Claude Ravache, Rene Heron) or show signs of decreasing utility (Irene Adler), he also means to betray the prime ministers and ambassadors, who had trusted his advice on the increasingly foreboding political climate, by instigating war.
A Civil Campaign: Byerly Vorrutyer, the man-about-town and general political stirrer. He has motives so indiscernible that it's very hard to tell exactly who he's actually betraying, and whether he's a double agent, triple agent... or what, really. Actually working for the government. We think.
Ivan:"You've lied and you're lying, but I can't tell about what. You make my head hurt. I'm about to share the sensation."
It's strongly implied that Byerly's contact/handler is Ivan's own mother, opening a new can of fractal worms in Ivan's suddenly illuminated head. Cue spit-take.
Another implied possibility is that his "blind drop" is Ivan himself (making the drop REALLY blind).
In The Vor Game we meet a more pathological version in Commander Cavilo. Having already vamped her way into command of a mercenary warfleet; she gets hired by a planet during a staredown with a rival, sells them out to the Cetagandan Empire, then backstabs both the Cetagandans and her own fleet for a chance at seducing the Barrayaran Emperor Gregor (who had slipped out of The Chains of Commanding after a drunken, halfhearted suicide attempt) into making her his consort. It is mentioned (though not by name) as being her downfall. If she had stuck with one plan, any plan, she could have probably pulled it off. But she's unwilling to follow through when she thinks something better comes along.
Miles (the series' protagonist) himself seems to suffer from a variant of this disorder (which is lampshaded in the series, especially The Vor Game and Memory). Rather than intentionally betraying allies and neutrals, he makes commitments (implicit or explicit) which he later can't fulfill without breaking another one. (He doesn't want to betray people, and he generally manages to juggle responsibilities and deceive people until he finds a solution. However, his skill at avoiding having to follow through with the final outright backstab doesn't prevent the lead-up from being its own form of betrayal.) The pattern is most clearly (and avoidably) showcased in the first book The Warrior's Apprentice.
The villain, Achilles, in Orson Scott Card's Shadow Puppets trilogy. By the end, he's betrayed Russia, India, Thailand, China, and the Hegemon. Also, he kills anyone who's ever seen him vulnerable, including people who help him out of said situation.
Fernand Mondego of Dumas' The Count of Monte-Cristo achieves success through this. First he participates in setting up Dantes so he can have Mercedes for himself. Then, during the Napoleonic Wars, he and his superior officer both desert Napoleon at the right moment, earning promotions from the new Royalist Regime afterward. Then, as a sort of mercenary in the Greek Wars of Independence, he is a well-paid commanding officer under Ali Pasha who he betrays to the Turks. Not only does he gain a fortune for this treason, but back in France everyone thinks he's a war hero and he ends up a general.
Lord Gro from E.R. Eddison's The Worm Ouroboros had a bad case of this, due to his desire to be fair and support the underdog. Eventually it did cost him his life, when he started killing soldiers on both sides in the middle of a battle to show there were no hard feelings.
Flashman - Flashman inevitably gets to see any conflict from both sides due to getting captured and/or turning his coat.
Lily, of Austin Grossman's Soon I Will Be Invincible. In her backstory, before the events of the book, she was sent back in time to Set Right What Once Went Wrong, did so, then decided to attempt to undo her changes so that she could go home. (This backstory is revealed to be false. She was originally Lois Lane to the Superman-like CoreFire before getting empowered and dumping him.) She became a supervillain, eventually hooking up with villainous Dr.Impossible, then left him for his Arch-Nemesis, the superhero CoreFire; as the story opens, she is just being recognized as an official member of CoreFire's team, the New Champions. She then provides Dr. Impossible with the last Plot Coupon necessary for his latest Doomsday Device. Doing so is what saves the world from the disaster described in her backstory, and lets Dr. Impossible beat the snot out of CoreFire. Then she backstabs Dr. Impossible again to save the world yet another time, before chewing out both him and CoreFire and leaving them tied up to the same post. Even at the end of the series, it's clear the only side she's on is her own, and quite effective at it. Ironically, she's transparent.
This seems to be a deep cultural practice of the entire Psychlo race in L. Ron Hubbard's Battlefield Earth. They spend so much time blackmailing and backstabbing each other its amazing their species manages to run an inter-galactic empire. Terl, the Earth franchise's security chief is a toxic example even amongst this crew: he needs to betray so badly it at some level it surpass rationality. It turns out that Psychlos have bad wiring in their heads.
A Song of Ice and Fire: Petyr "Littlefinger" Baelish, the resident Magnificent Bastard. He's actually pretty upfront about being a chronic backstabber, but no one takes him seriously. He allies himself with Eddard Stark, causing him to believe that he had the resources to move against the Lannisters. But then when it comes time to act, Baelish betrays Stark to the Lannisters. He then frames Tyrion Lannister for the murder of his nephew Joffrey, causing House Lannister to tear itself apart - and making way for his new allies, the Tyrells, to take control of Westeros. With each successive betrayal, Baelish's own personal standing is increased, going from an unappreciated civil servant to the ruler of two of the Seven Kingdoms, and with Stark's eldest daughter, Sansa, as his protegé and one of the candidates for Queen Cersei's throne. And then we learn that the murder that made Stark want to get revenge on the Lannisters (Jon Arryn's) was committed by Baelish all along, having manipulated his wife Lysa into doing it..
Everyone assumes this of Jaime Lannister "the Kingslayer", ever since he killed King Aerys II while serving as part of his Kingsguard. Aerys was planning on burning down the entire capital city and the entire population thereof rather than allow his enemies to conquer it; Jamie only killed him to prevent this from happening. When he gets a POV chapter later in the series, we see that he's completely aware of his reputation and enjoys utilising it to his advantage.
Funnily enough, Jaime Lannister stabs Aerys Targaryen in the back..
In Larry Niven's Known Space, Pak Protectors were in a perpetual state of war, because every one was biologically hardwired to serve the short-term interest of its own clan. Even when clans tried to be allies, the protectors would instantly, involuntarily backstab each other as soon as any opening appeared. In one book, a protector is friends with the main characters and needs them to save its whole world, but finds itself trying to kill them anyway because they are a threat to some of its own relatives.
The way to get ahead at Unseen University is "by way of dead men's pointy shoes." In other words, kill the guy above you and steal his shoes and hat. Rinse, lather, repeat. Since the elevation of Mustrum Ridcully as Archchancellor this process has been halted, by virtue of him being virtually unkillable, resulting in a lot more permanency among the other senior wizards as well as backstabbing decreases.
Lord Hong in Interesting Times. He helped along the revolution himself just so he could start a counter-revolution, he more-or-less cooperates with the other feudal lords while maneuvering for the crown, he has his minions killed after explicitly promising them to not give any orders to that point, he has no problem telling his soldiers lies which run exactly contrary to what they were told a few hours ago (and expects them to believe him!) and last but not least, is very clear on it that it's fine for a few hundred or thousand of them to die, because that's what they are for. Oh, and he had the emperor killed (stabbed!), but that's part of the power routine.
X Wing Series Ysanne Isard. Nominally always working for the Empire, but after the Emperor died, she was just working for herself. Later in the series, Baron Soontir Fel and Gara Petothel are both accused of this. It's untrue on both counts.
Ludovico in Leonardos Swans. He does this both to his wife and his political allies.
First we have Gundleus from the first book. Already King of Siluria, Gundleus is set to marry Uther's daughter in the wake of Uther's death and be the regent for Uther's infant grandson, who will be the future High King. Instead Gundleus gets greedy and decides to shoot at becoming High King himself, murdering his wife to be and attempting to kill the baby as well. After Arthur captures him alive and treats him well, Gundleus promptly sides against Arthur in the next round of warfare among the British kingdoms when it looks like Arthur is going to lose. Oh, and in addition to killing his wife and attempting infanticide, Gundleus also rapes another character and rips out her eye. Fun guy, and particularly notable because even without doing any backstabbing he would in a position to wield enormous power.
Bishop Sansum is a Corrupt Churchman who operates on a single rule when it comes to the endless wars and political squabbles between the British kingdoms: be on the winning side. As soon as one faction gets the upper hand, Sansum is sure to make himself just useful enough to them that he'll survive and prosper regardless of who actually wins.
Also, in a very different take on the legend than usual, there's also Lancelot.
Finally you have his (arguable) betrayal of himself, when he undoes everything he's been working towards in order to save himself from eternal loneliness.
Raistlin's half-sister Kitiara steps up to the plate:
She betrays Tanis by seducing his best friend Sturm.
She betrays all of the Companions by not honoring her oath to them and by joining the Dragonarmies.
She betrays Laurana by luring her to a false parley and kidnapping her.
She betrays Raistlin and Iolanthe by trying to kill all wizards.
She betrays Tanis again by offering to spare Laurana when she has already decided to give the elfmaid a Fate Worse Than Death.
She betrays Ariakas by plotting to overthrow him.
She betrays Lord Soth by letting Tanis take Laurana.
She betrays Raistlin again by having Lord Soth try to kill Crysania.
And she betrays Dalamar by stabbing him.
Codex Alera: Aquatainus Invidia will betray anyone and everyone in order to secure greater power for herself and, later, survival. Any character who has dealings with her not already possessing it quickly develops enough savvy to try to take Invidia's sudden but inevitable betrayal into account.
In the last book, The Vord Queen doesn't even have any emotion reaction at all when it's her turn to be backstabbed. She explains that Invidia IS this trope and doing anything else simply would not be Invidia.
His Dark Materials - Marisa Coulter. Spends an awful lot of time trying to capture her daughter, Lyra. Then it turns out that she was trying to protect her. Then she finds out about the prophecy. Then she starts trying to capture her again, with the help of some old guy. Then she poisons him and kidnaps Lyra to protect her from the Church, who want to kill her. Then Lyra escapes and Marisa goes over to Lord Asriel's side (the people who want to destroy the Church). Then she betrays him and defects back to the Church. Then she stops the Church from destroying Lyra and it turns out that her only intention was to stab them in the back. Then she helps kill the angel who has taken God's place, overthrowing the Authority in all worlds forever. Then she dies.
Many characters in Jack Vance's books, most notably Cugel the Clever, who for most of his two books will steal from, exploit, murder, or in some other way take advantage of anyone who has something he wants, or, really, even those who do not. Cugel is squarely the protagonist and Vance is a master of neutral treatment — Cugel's un-judged behaviour can be quite breathtaking.
Vissers 3 and 1 in Animorphs. Probably other officers of the Yeerk army as well, but these two are most prominent, constantly working to undermine each other's position, even if it harms the greater cause and helps the Animorphs.
The Stanleys in The Sunne In Splendour. They keep betraying people even when it doesn't actually improve their situation. Since this is an historical novel, that was Truth in Television. The Stanleys were known as being turncoats.
"Truces in this land are made to be broken," he answered grimly. "He would break his truce with Jihiji. And after we'd looted the town together, he'd wipe me out the first time he caught me off guard. What would be blackest treachery in another land, is wisdom here.
Lu Bu of Romance of the Three Kingdoms manages this in truly appalling fashion. The Reader's Digest version would go: murdered his master for a horse, murdered his next master for a 16 year old girl, became a rebellious warlord, betrayed his friend Liu Bei, and finally tried to sell his services to his sworn enemy Cao Cao. Cao, being a Magnificent Bastard and Dangerously Genre Savvy, said simply, "Strangle and expose."
In the Chung Kuo novels there are many betrayals - the upper levels of society run on Machiavellian scheming - but the supreme Wei Chi Master Howard DeVore outdoes them all. At first his betrayals seem to follow the logic of power, and he gets away with them all - he's slippery - but in the end he betrays everyone, that is, the human race.
In Doc Smith's Lensman novels, the Boskonian culture, spread through two major galaxies, runs on this trope. Everyone moves up through assassination and/or betrayal of their superiors. And they get away with it, as long as they protect themselves from others assassinating/betraying them, because that's how you legitimately advance in their culture. Kim Kinnison goes undercover and works his way up to supreme dictator of an important planet and all its dependencies by a series of betrayals and assassinations, and he's widely admired and respected for this.
Uwe in The Black Swan toes the line between this and Manipulative Bastard. He allows Queen Clothilde to believe he is helping her set up her son for a tragic 'accident' which will let her keep the throne for life — in reality he is setting her up for Baron von Rothbart to destroy her. Unfortunately for Uwe, the Baron rewards him as a traitor deserves.
In the second Time Scout book, Wagers of Sin, Chuck Farley is a master of this. And he gets away with it.
In the Age Of Fire series, Infamia takes the cake. She's betrayed her mate, abandoned her other mate, defecting from her new employers after leaving in exile, then betraying her new king, and then betraying her mate again (who was the first one she betrayed). Subverted in that, except for the first two incidents, she was possessed by the Red Queen.
This isn't even a spoiler in The Clique series of YA novels, over the course of 13 (14 if you count the prequel) books the middle school girls, including Claire, back stab each other at least thrice. Prize goes to Massie and Alicia, who back stab each other so much it's not hard to lose count.
The society in Cyril Kornbluth's classic dystopia The Luckiest Man in Denv operates this way. In particular, the generals appear to spend more time intriguing against each other than prosecuting the war against Ellay. The protagonist, Reuben, is also no slouch when it comes to backstabbing his own superior officer.
The Eunuch Narses as depicted in the Belisarius Series has a genuinely pathological form of this. For his first (and by no means last) betrayal he, Grand Chamberlain of the Roman Empire and the only high official the Ruling Couple completely trusts, commits to a conspiracy that would cost the life of the closest thing he will ever have to a daughternote (to his credit, when the whole thing goes south he goes out of his way to save her before escaping) in the hopes of becoming the Man Behind the Man for Justinian's replacement. He hates himself for it, and is convinced he will be dead of old age (and damned to Hell) in a few years no matter what, but he just... can't... stop.
In Villains by Necessity, by Eve Forward, the neutral druids had to betray whichever side was strongest and help the underdog because if the forces of light or the forces of darkness became completely dominant, the world would be subsumed into the raw metaphysical force of good or evil because of it (depending on which one they fell into). When they stopped helping the good guys because good was becoming too dominant, they faced the fact that evil wouldn't trust them and they'd just stuck the knife in the back of good, meaning the druids got wiped out between the two.
Live Action TV
The Wire: Stringer Bell betrays three people, all of them main characters, and all of them considering him trustworthy. They are, in order, Wallace, D'Angelo (coming and going), and Avon Motherfucking Barksdale.
Tony Almeida in the seventh season of 24. He betrays Emerson's group, which he claims he had actually been loyal to at one point for serving as a deep cover agent for Bill Buchanan, then betrays the FBI by killing Larry Moss after thwarting Juma and Hodges' plans in favor of the masterminds behind the conspiracy, all so that he can meet their leader face-to-face and kill him.
The entire genre of reality television (or at least those shows based upon forming teams and alliances) is built around this.
The Grant clan from Big Love are all like this. By this point, you need one flow chart just to figure out who's related how to whom (living on a xenophobic polygamist compound where wives get swapped around at the whim of the Big Boss can do that to you) and at least three more to keep track of who's currently trying to have how many of said relatives jailed, killed, or terrorized into submission (and who's just in it for the book deals).
The Daleks of frequently betray any and all individuals/species that think the Daleks are working for them, almost always with a cry to "Exterminate!" the betrayee.
Pretty much lampshaded in "Victory of the Daleks" where a group of impure Dalek refugees manage to activate a device which makes shiny new model "pure" Daleks, which then proceed to immediately exterminate the old Daleks, who die willingly.
"Genesis of the Daleks" makes it plain where they got it from: their creator, Davros, also proves to be a good example of this trope. The fact that he does not see their betrayal of him coming adds a nice layer of irony to the episode, and the fact that they have proceeded to repeat this betrayal multiple times, and that each time he has failed to see it coming, just adds to the deliciousness of it.
The Master is also a fan of the tactic, but he is backstabbed almost as many times as he is the one doing the backstabbing.
The Sontarans. They backstab Irongron, the Vardans, the Androgums, and Luke Rattigan.
Fifth Doctor companion/would-be assassin Turlough originally met the Doctor after the Black Guardian offered the exiled alien schoolboy a lift off planet Earth in return for killing the Doctor. He abandoned and betrayed the Doctor pretty much anytime things got too dangerous, even after Fivey forgave him for the whole, you know, attempted murder thing. However, he always seemed to redeem himself by doing something heroic, especially in his last episode, Planet of Fire.
Sikozu was an embodiment of this trope, her only consistent trait (besides total arrogance) being her capacity for 'sudden and inevitable betrayal'. Close to the end of the fourth season, however, she looked to be outgrowing this character flaw- only for the Scarrans to employ her as a spy during The Movie. Her comeuppance finally came at the hands of her current boyfriend Scorpius, who beat her to a bloody pulp and left her to die.
Grunchlk in the episodes "Die Me Dichotomy" and "Season of Death" qualifies: while overcharging the crew of Moya for various medical services, he quietly betrays them to Scorpius. However, when Scorpius arrives with a squad of heavily-armed Peacekeeper commandos, Grunchlk panics and releases a Scarran warrior from stasis in an attempt to hold the attackers off. And it turns out that the Scarran was also double-crossed by Grunchlk...
During season 4, Crichton believes that Scorpius suffers from this disorder after he joins the crew. Crichton has good reason to be suspicious of Scorpy, but seems to believe that Scorpius is going to try and backstab him at the most idiotic times: for example, in "I Shrink Therefore I Am" he gives Scorpius an empty rifle just in case any treachery occurs- while they're both stuck on Moya, with all their escape ships disabled, and being hunted by bounty hunters with no interest in negotiations. Lo and behold, Scorpius isn't that dumb. Eventually, Crichton decides that Scorpius can at least be trusted to a certain extent after several incidents where not only remains loyal but even puts his own life on the line to save the day at least twice. Unfortunately, after being used as bait for Talikaa, Scorpius decides he's had enough of his role as Sixth Ranger and backstabs Crichton so masterfully that it takes him two episodes to figure out who was really behind Aeryn's kidnapping.
Rygel. Back stabbing was his default setting. Circumstances seem like Rygel might be somewhat inconvenienced? Time to throw everyone else to the wolves.
Saffron. In the episode "Trash," when she called upon Serenity's crew to help her steal the Lassiter, the heroes cooked up a Batman Gambit to take her down, which took advantage of Saffron's "sudden, but inevitable, betrayal".
Jayne - who repeatedly try to sell out his own crew for money or to become the captain. Naturally, Mal repeatedly thwarts these plans and generally beats Jayne up or threatens to kill him... but he's a slow learner.
He also betrayed his original crew in order to join Serenity. Why? Well, they were robbing Serenity, and Jayne's share was 7%. Mal offered him 11% and his own bunk. Several shots to the back later, Jayne was Serenity's newest crewmember.
In The Movie, Jayne tries to go behind everyone's back and throw River off the ship once he realizes how much a threat she represents. River advises Jayne of his fallacious reasoning via ceiling-launchedcranial trauma.
Star Trek's Mirror Universe is a living example of this trope. Officers assassinate their superiors to get ahead in the ranks. In The Original Series, the Mirror Universe's Pavel Chekov tries to do in Captain Kirk. Enterprise's two-parter Mirror Universe episode had plenty of this too, with Commander Archer betraying Captain Forrest and several of Archer's crew betraying him and each other in turn. Part of what's most amazing about the crew is that they still manage to work together even with some of the people who very cruelly betrayed them. The hideously scarred mirror Tucker, for instance, was still loyal to mirror Archer even after spending four hours in the Agony Booth for a crime he didn't commit and only being released when crew members loyal to Forrest retook the ship from Archer.
Garak (whom Dr. Bashir is constantly trying to decipher) and Quark, whose alliances change based on his own benefit. Quark's family often have to play the same games - which Quark approves. Dukat is another good example, as he is even trusted by his allies even after a third betrayal.
Most Cardassians that appear in the show are either in some kind involved with the Obsidian Order, or on the run from them, which makes Chronic Backstabbing appear like the Cardassians hat.
Mohinder Suresh seems to be doing a lot of this, although it's mostly due to him being an atrociously Horrible Judge of Character than any sort of malicious master plan on his part.
HRG, Mama Petrelli, Nathan Petrelli, and Sylar. More backstabbingness than you can shake a knife at.
In Kamen Rider Ryuki, Satoru Toujou/Kamen Rider Tiger has this so badly, he's far more dangerous to people he considers allies than his enemies. In Kamen Rider OOO, according to Ankh, the Greeed as a species suffer from this, though he's an exception because he'll let you know upfront he'll betray you if you're no longer of use.
Brainiac. Unless you are Zod, working with him will end up with you getting backstabbed.
During season eight, Chloe successfully manages to stab Clark, Jimmy (her fiance and then husband), and villain Davis in the back almost simultaneously. Then in Season 9 she implements Orwellian measures against Clark's will, ostensibly to "protect Metropolis." This includes putting up cameras in Clark's house and casually mentioning that she spends large chunks of the day surfing through everyone in Metropolis's cell phone conversations.
Tess Mercer. By season nine, there's really no reason for anyone on any side to believe anything she says.
Chloe: At this rate, you're gonna run out of people to betray.
She manages to go the entirety of Season 10 on the Face side of things without actively betraying anyone. The other characters are aware that she is this trope, though, because whenever something bad happens, they accuse her of turning on them.
Here's a fun game. Watch Smallville and have a drink every time someone is or is revealed to be lying to, manipulating, or downright betraying another character. Two drinks if their last name is "Luthor", "Teague", or "Lang".
Alex Krycek from The X-Files, easily. Good luck figuring out whose side he's on, and if (you think) he's on your side? Well, just don't turn your back to him.
Basco Ta Jolokia from Kaizoku Sentai Gokaiger will betray anyone he works with. Whether it's the Red Pirates, the Zangyack or his own Morality Pet. Suffice to say, he's one of the most dangerous and despicable villain in the series.
In Alias, Mr. Sark was known for his "flexible loyalty."
Charles Brandon of The Tudors may count as this. Season One he allies with the Boleyn faction against Wolsey, Season Two with Cromwell, Chapuys, and the Seymours against the Boleyns, and in Season Three with the Seymours (and Francis Bryan, whose motive never was explained) against Cromwell. Season Four he's finally sick of plotting, but he really doesn't like the Seymours. Cromwell also could count as this. He owed his career to Wolsey, but still refused to help him in his time of need. He also owed much of his later rise to Anne Boleyn but still frames her for adultery and treason. But, actually, the only one he's truly loyal to is Henry, who he never betrays. This does not save him.
Psych: Shawn's uncle Jack offered fifty percent of a fortune in Spanish gold to his nephew. And his partners. And his other partners. And the guy at the muffler shop. And the guy at the Chinese restaurant. Yes, that's three hundred percent.
Shawn and Gus frequently betray one another. In fact, there's a moment of selling out between one or both of them in almost every episode.
Stargate, the Goa'uld in our galaxy, the Wraith in Pegasus.
Done when funny in Top Gear - the three presenters take it in turns to team up two-against-one, before someone invariably switches allegiance and starts making fun of their former ally.
Harmony on Angel is nice and good-natured, but she is an evil soulless vampire. At the series finale, she sells out the team to their enemies. It's okay, Angel knew she would do that and built it into his plan. He fires her, but gives her a letter of recommendation.
Harmony: You're the best!
When Angelus is unleashed he discovers a demon that blocks out the sun. Vampires rule the day as well as night, and when Faith tries to stop him he beats her. Angelus had won, and the demon is about to kill her, then Angelus picks up the Villain Ball and grabs it hard by destroying said demon. Not for power, not so he could kill Faith himself, just because (he also doesn't like being told what to do, and his intention was that the demon would only weaken her). Unfortunately for him, this undoes the sun-blocking spell, something he had hoped was "just Angel's retarded fantasy".
Omen on Dark Oracle suffered from this as part of his Heel Face Revolving Door. Somewhere in the backstory he betrayed Doyle and was turned into a frog as a result. When he reappears he romances Cally, only to betray her and use her as a pawn against Doyle and Lance. He later promises Cally that he will rid her of Blaze and Violet if she returns his humanity. She does so, but Omen's attempt at killing them only makes them stronger and results in his imprisonment. After being freed by Vern he offers Vern a chance at revenge on Lance, only to betray Vern by taking it too far and trapping Lance in the mirror world. When Cally comes to him for help he betrays her by swapping out Lance for Blaze who he was really working for, and helping them set up a curse that will eliminate Cally as well and let Violet escape. Finally, he betrays Blaze & Violet, helping Cally free Lance and dying in the process. Phew.
Baltar from the classic Battlestar Galactica. He betrays his own people to the Cylons, then turns around and betrays them in the last episode ''The Hand of God’’.
In the second-season paintball game on Community, Chang continually teams up with and betrays almost every pack of combatants who will take him, until he is relentlessly shot by the study group, who saw right through his Chronic Backstabbing Disorder.
This is the entire point of Game of Thrones. (It's all in the name.) Just about everyone wants to rule the Seven Kingdoms of Westeros, and is prepared to lie, cheat, and murder their family members and supposed allies to do so. The few (sane) people who don't want to rule have to suffer the consequences.
In the Headstones Tiny Teddy the eponymous character is described as willing to sell out everyone, and he proves it by strapping timed explosives to his follower and sending him into the mansion belonging to the guy whose money he gambled and snorted away in an attempt to escape the debt.
Pink Floyd's song "Dogs", from Animals: "You have to be trusted/By the people that you lie to/So that, when they turn their backs on you/You'll get the chance to put the knife in."
"Backstabber" by Ke$ha no?
Bret Hart had this during his entire tenure with World Championship Wrestling, but especially in the first couple of years or so, where it seemed sometimes even the writers were confused as to whether he was a good guy or a bad guy at any given time. In late 1999, he got the biggest push of his WCW career, winning the World Heavyweight Title as a face— only to, within a month or so, turn on former partner and friend Goldberg and re-form the New World Order.
Shawn Michaels was teaming up with John Cena to become a championship tag team. Given that they were slated to compete at Wrestlemania for the WWE Championship, the team seemed shaky but HBK was determined to keep Cena at 100% for Wrestlemania. Cena was consistently worried that HBK would turn on him like he had done with every single person and team he had ever worked with. Inevitably, yes, HBK turned on Cena.
On a larger scale, the NWA suffered from this to the point of ruination with any member who's popularity had grown ending up leaving and competing against them. The major organizations that defected, there were many more minor ones, were the AWA the WWWF, JCP, ECW, and TNA.
Ever since Kane debuted, Paul Bearer has been switching allegiances between him and The Undertaker. It actually started when Bearer abandoned Undertaker for Mankind after six years of managing The Undertaker.
Christian turned on EVERY partner he's ever had, until AJ Styles & Tomko turned on him to join the Angle Alliance and Christian underwent a Heel Face Turn, which carried over to his second WWE run. Lampshaded early in his TNA run, as Jeff Jarrett pointed out to Sting that Christian couldn't be trusted, and Christian retorted that Edge & Chris Jericho would vouch for his loyalty; before immediately remembering that he did betray them and remarking that calling them wouldn't be a good idea.
Subverted at Wrestlemania XXVII in a Meta Twist: everyone and their mother was expecting Christian to turn on Edge (who had been Those Two Guys all their careers) during the match with Alberto Del Rio and yet amazingly, this wasn't even hinted at during the match. Christian never turned and everyone was rather surprised and happy. When Edge retired days later to a legit injury, it meant that instead of having Edge's last match be a loss due to the betrayal of his best friend, it meant he went out and retired as the champ.
Matt Morgan in TNA, for a while. He turned on Abyss, he turned on Hernandez, he turned on Immortal... it took until 2012 for Crimson to turn on him. It seems only a matter of when he and Joey Ryan will break up.
In general, nearly every successful tag team will eventually end with one member betraying the other. This inevitably results in either an immediate Face Heel Turn for the betrayer or a Heel Face Turn for the betrayed, depending on whether the team were faces or heels, and leads into a singles feud between the two former partners.
And then there are The Seven Steel Thanes of New Phyrexia: backstabbing each other and any other Phyrexian higher-ups is the only thing they ever do.
Ambassador Laquatus of the Odyssey Cycle switches sides whiplashingly often. You'll usually see him plotting his betrayal before he even makes the alliance.
Diplomacy can be a bit of a subversion. The player who stabs at every chance quickly finds himself friendless and doomed. Skilled players know that a long-term alliance is one of the most valuable things you can have, and only stab when doing so is necessary for survival or likely to win the game.
The Skaven of Warhammer, which is the only reason they haven't taken over the whole Warhammer world. We should probably be thankful they consider Chronic Backstabbing Disorder to be a desirable way of life.
True Neutral people in the old AD&D were described as switching sides to whichever one was weakest, to preserve the "balance" between good and evil. This was dropped in later editions, due to being insane.
Like the Skaven, the Drow from Dungeons & Dragons live underground, keep slaves, and betray anyone whose death would provide the slightest benefit. Their goddess, Lolth, encourages this behaviour. It's gotten to the point where in some of the Forgotten Realms novels, the Running Gag is that a drow found dead with a knife in her back is considered to have died of natural causes.
Paranoia: Backstabbing your fellow players is the point of the game.
Munchkin is based on the trope, so much so that the phrase is part of the tagline. You'll help them with one difficult fight, then do everything in your power to see that they lose the next one. Gets particularly nasty towards the end of a game, when players will frequently form alliances to stop someone from winning, then immediately side with that person against their former allies. It's all Rule of Fun and Rule of Funny, though, so hopefully it won't be played by anyone who holds grudges.
The name comes from the Player ArchetypeThe Munchkin which is often prone to this due to their goal of trying to win games that aren't supposed to be competitive.
For In Nomine, Malphas (Demon Prince of Factions) is assigned with creating divisions in society, from mere distrust to full Chronic Backstabbing Disorder. Not surprisingly, he instigates so much backstabbing in Hell (both by himself and by making others paranoid enough to do it) that it's amazing that he hasn't betrayed Lucifer (yet).
A supplement to the French game In Nomine was based on introduces the secret A.P.H.T.E. organisation, Malphas's pet project. Truly amoral, this organisation can be hired by anyone, including humans, to ruin anyone else's life. The canon operative? Monica Lewinsky.
The Ebon Dragon, in Exalted, is essentially the cosmic principle of selfishness, deception, betrayal, and general jackassery. He doesn't even need a reason to betray one of his "allies"; he'll do it just to spite them. He is the reason you can't have nice things.
He doesn't just betray his allies, he betrays himself. He's only crafted one jouten (physical body - most Yozi have multiple different bodies, often operating simultaneously) because he knows that if he crafts any more, they'll try to turn on him.
In Warhammer 40000, the Dark Eldar are quite fond of betraying each other, and are probably a greater threat to each other as they are to their actual enemies. Also, followers of Chaos, with exception of Nurgle and his followers, are willing to turn on each other, especially Tzeentch and his followers, being The Chessmaster and Magnificent Bastard that he is.
The Dark Eldar do, however, have enough sense to leave the backstabbing knives at home when they go on raids. Kharn the Betrayer though? Not so much (though in all fairness, he'll probably stab you in the front).
The C'tan known as the Deceiver is another master of this- he constantly switched sides during the war between the C'tan and the Old Ones, and when neither side would trust him, he started using disguises- And, according to the Necron Codex, the mistrust sown between the various races serving the Old Ones by the Deceiver's machinations probably did more for the C'tan war effort than the other three remaining C'tan combined.
That all can be said about most if not all factions in 40k, with the possible exception of the Tyranids (and even there players can find reasons to fight each other) and the Imperium (who still infight all the damn time, but for differentreasons). Some races are just better at it or backstab more often.
The Inquisition. May be a crucial part in a Dark Heresy game.
Steve Jackson tends to love this in various games, especially:
Kindred Of The East who follow the Dharma of the Thousand Whispers, which upholds the principle of balance through diversity, are known for this, since to maintain their Dharma they have to see life from different perspectives, for example by changing allegiances.
Vampires in general seem to have this as their species-wide hat. After all, the happiest vampire in the world is the last one.
The Nephandi don't really have it much easier, though it's kind of justified, given that they're an order of total dicks and Evil Sorcerers.
The Seers of the Throne have institutionalized CBD. Every member of the order is looking to usurp and replace their superior, the guys at the top (the Ministers and tetrarchs) are looking to Ascend and join the Exarchs, and the Exarchs are looking to outmaneuver and gain power over each other. It honestly is a wonder they manage to get anything done.
Anyone who forms a pact with the demon lord of betrayal is kind of obligated to act this way in The Dark Eye. Even if they don't want to...
Though the stories paint them as justified (in a sort of "We're backstabbing you because you backstabbed us" counter-betrayal way), Battle Tech's Gray Death Legion eventually gains a reputation with the Mercenary Review and Commission Board as this, having a long, demonstrated history of attacking their employer's forces, even when they do so to stop rebellions and bring down rogue generals. In short, they have a history of doing the morally right things by doing the legally wrong things.
Vezon:It's all a trick, you see. They want me to pretend to betray them. They want you to concentrate your forces here against an attack that won't come. But I decided: Why pretend to betray them when actually doing it would be so much more fun?
The Piraka, since they double-crossed each other several times in the 2006 storyline.
Roodaka, especially because she betrayed BOTH SIDES in the Makuta/Dark Hunters war.
The Makuta. Teridax betrayed Miserix and took over, and Icarax teamed up with Krika to do the same against old Terry, (arguably, Icarax was probably going to kill Krika, or vice versa, seeing as they had different views).
The Masyafs don't appear in Assassins Creed III, but Benjamin Church plays the trope straight. We don't see most of it, but in his database entry Shaun might as well have diagnosed him with this disorder. He even said that he wouldn't be surprised if Chruch betrayed himself. By the time we get to go after him, he's betrayed and left the Templars (whom saved him from being butchered early in the game) and betrayed the Patriots. Twice. The first betrayal in that list was so bad that Haytham personally searched for Church, decided to enter an Enemy Mine situation with Connor, and when he finally catches him, he beats the living shit out of him. And when Connor steps in and tries to interrogate him? He just grins and says "Go to hell" before getting stabbed. What a dick.
Baldur's Gate 2 has a marvelous example where the PC himself can do this: A silver dragon asks you to get her eggs from a drow city. The drow want to feed the eggs to a lesser demon lord. The daughter of the Evil Matriarch wants to betray her mother so asks you to switch the eggs for fake ones. Her Defector from Decadence lieutenant offers another double-cross, by providing a SECOND set of fake eggs. So you can now give the Evil Matriarch the fake eggs (making the demon lord kill her), give the daughter the fake eggs (making the demon lord kill her too), and then, finally as a Crowning Moment of Awesome you can hand the real eggs over to the demon lord anyhow, in exchange for some spiffy rewards. That is, if I'm counting right, a quadruple-cross.
Only a triple-cross at best, since of the five people involved three get what they want. (The Lieutenant gets his target killed, and either the demon or dragon gets the eggs.)
Backstabbing the mother = double-cross. Backstabbing the daughter too = triple-cross. Finally backstabbing the dragon as well = quadruple cross.
And there is also the fact that after you give the Dragon her eggs, she teleports you to a gate where you can have a fight with Drow before she opens it. It is possible to kill her during that battle in order to get her blood (used for some secondary quest).
Another lovable example from the same game is Saemon Havarian. He first appears as a captain hired to take you to Spellhold, where it turns out he was actually in the employ of Irenicus all along and had doped your meals on board for an easy capture. He then betrays Irenicus, helps you to boot him out of Spellhold, and offers you a ride back to the mainland. As it turns out, his ship has 'tragically' been stolen in the meantime without his knowledge, so he obtains your services to steal him a new one and rewards you with a Githyanki Silver Sword... Then, when the Gith show up to claim it, he abandons you to them! You also encounter him in ToB, where as soon as he sees you he tricks some local thugs into attacking you to get himself off the hook. Finally, he shows up to offer to show you a hidden backdoor into the Big Bad's lair... Which has an ambush outside of it, ready to take you prisoner. Unfortunately for the ambushers they had instructed him to dope you again so they can take you without a fight... And he didn't, making it a double-cross of both ambusher and ambushee at the same time. That's at least seven betrayals for all of two appearances.
In Final Fantasy Tactics, Chronic Backstabbing Disorder has apparently become a pandemic. One character in particular (Delita Hyral) is arguably the reigning king of this trope. As the game goes on it becomes practically expected of him to stab whoever he appears with. And he is one of the good guys.
Alex of Golden Sun suffers from a severe case of Chronic Backstabbing Disorder, which is made all the more confusing because of the ambiguity over which side is "good" and which is "evil."
As of the end of the second game, he appears to be the only member of the main cast who was unambiguously evil. Then the third game comes around and he's back to being infuriatingly enigmatic.
Revolver Ocelot of the Metal Gear franchise, obviously. In almost every game, he's pulling a Fake Defector from one nefarious organization to another, sometimes through multiple fronts.
And Metal Gear Solid 4: Guns of the Patriots reveals he was, in a weird sort of way, on Solid Snake's side the whole time, though that he helped cause the PATRIOT mess as well prevents him from being the true hero of the story.
In Metal Gear Solid Peace Walker, despite not appearing, the backstory revealed he'd pulled the hitherto unprecedented feat of backstabbing his own mother before he was born.
The only other person who backstabs as much as Ocelot and gets away with it is Naomi Hunter; she pulls several in her first appearance and in Guns Of The Patriots she betrays the good guys and the bad guys multiple times, confusing everyone and making the heroes feel sorry for her. It is generally believed that her eventual goals were good, but man. Did she have to be so roundabout about it?
Actually, the Patriots themselves probably qualify as such as well, considering how they usually manipulate people into acting in accordance to their will (even feeding some people ambitions to betray them in order to carry out exactly what was intended all along), and apparently even out-backstabbed Ocelot (as they deliberately kept some information from Ocelot about the S3 Plan, although given his status as a founder of the Patriots as well as Naomi knowing what the Patriots were planning to do, it's likely he at least deduced what their true plan was anyways.).
His old info card described him as "a Double Reverse Quadruple Agent whose reflexive suspicion is entirely justified." In any event, no one really knows what the Spy of either side is up to.
Dimitri Rascalov of Grand Theft Auto IV backstabs every alliance he makes throughout the course of the game, regardless of what outcomes are chosen. At the start of the game he sells Niko Bellic out to a debt collector after convincing Niko to kill his boss Faustin. He is behind the diamond theft from the Chasid Mafia, and he doesn't change at the end of the game, without revealing any spoilers
Much, much earlier, in Grand Theft Auto III, the PC is prepared and often encouraged to assassinate his allies if another client pays more. The mostly-justified killing of Salvatore Leone, the Yardie-sponsored shooting of former allies among the Diablos, the drive-by shooting of Kenji Kasen... the list goes on.
And this is all in the name of tracking down Catalina, who has a few backstabbing issues of her own.
In Fate/stay night, Unlimited Blade Works route, Archer switches sides and then betrays his new allies. Everyone naturally expects him to be a Fake Defector, but he then attacks his original side. It's all part of his plan to cause a Temporal Paradox... but only sort of, since he actually exists outside of time, apparently as a plot device specifically meant to prevent such a paradox.
It's also kinda inverted to, as we discover from Archer's memories that he had been betrayed by everything while pursuing his ideal, by the people he saved, etc, etc, to the point where he was betrayed by his own ideal.
Mortal Kombat's Tanya either betrays or seeks to betray every master she works for.
It's standard for any villainous character's ending to involve them killing the Big Bad and taking his place. In Deadly Alliance there are two Big Bads; both having displayed CBD for the entirety of their appearances. Guess what happens in their endings.
In Shiren The Wanderer for the Wii, people are betraying each other all the time. The character named Sensei is supposedly your uncle/mentor, then joins a hulking bandit leader and tries to kill you. He later rejoins you casually. Asuka rescues you, later fights you for like five seconds (still having access to the Bag of Sharing) because she worries you will accidentally destroy the world. She joins you again when you defeat her. Also, I think some villains kill each other off for acting dishonorably.
Final Fantasy XII, oh my! Among various other political machinations, House Solidor (The Archadean Emperor's family) all seem to have this. The implied background is that the eldest two sons, possibly on separate occasions, plotted against Emperor Gramis, who had the third son, Vayne, kill them. During the game, Gramis plots against Vayne, correctly predicting that Larsa, the youngest son, would make for a better and more stable Emperor. At the same time, The Senate is trying to seize power from House Solidor, particularly fearful that Vayne will take the throne. At the same time, Vayne plots against Gramis, The Senate, and Larsa, framing the senate for Gramis' murder, so that he can take the throne before Larsa can. As the plot goes on, Larsa plots against the Archadian war, making contacts with rival and conquered countries to make peace. In the climax, the brothers actively raise their swords against one another.
In Tales Of Symphonia, Kratos and Yuan go from helping you to backstabbing you to helping you to backstabbing you, back and forth constantly. There's also Zelos, who is playing several of the factions of the game up against each other so he can join whoever's the winning side, but does so considerably more subtly.
Axel in the Kingdom Hearts series has this problem. He is part of an alliance with Marluxia and Larxene to take over the Organization... but he betrays them because he's actually The Mole. Zexion and Vexen oppose Marluxia and Larxene's plan, so Axel should be aligned with them, right? Nope, kills them both. Turns out Axel's working with Saix and the two of them want to take over the group themselves, killing other traitor factions and loyalists that would get in their way. But then Axel becomes friends with Roxas and Xion, and leaves Saix behind. And then he (semi-accidentally) betrays them too!
Organization XIII in general has this problem. Almost all of them has had some scheme going at one point or another. In fact, it's the reason they ended up The Soulless to begin with. Exceptions are Demyx, who just wants to play his sitar; Luxord, who just wants to play poker with Marluxia; and Roxas, who just wants to eat ice cream with Axel and Xion— (apparently enough to try to take down Riku and the entire Organization just to have a chance to revive Xion).
In the first Bastila falls to the darkside after being captured by Malak, despite the fact you could have easily defeated him at the point of capture, and in the second Kreia reveals herself as Darth Traya, who has been manipulating you from the start.
Kreia actually has a philosophy on betrayals, seeing such things as necessary!
In both, you get the chance to betray everyone, from small families on Dantooine to your True Companions.
In the first game, the "GenoHaradan" missions. Hulas, the Rodian who gives you all the missions, gives you a final four missions to kill 'criminals', later revealed to be other "Genoharadan" leaders he has hired you to kill so he can assume sole power. Then he betrays you, but has the pleasant gentlemanly nature to set a time and place on Tatooine, although he tells you to come alone while he brings a small gang.
Also in the first game, while infiltrating a Sith training academy, the academy master's apprentice knows that her master is planning to kill her, and asks you to help her when the time comes. You can then tell the master, who will tell you to play along but turn on the apprentice when the time comes. You can tell the apprentice about this, and she will ask you to play along but, again, support her when the time comes. Whichever one you choose at the showdown will naturally try to kill you immediately afterwards.
You can thwart the apprentice from killing you by appealing to the bit of lightside still in her: You can later find her at the Dantooine academy if you do.
Even better, when the time comes to do the betraying, you can betray them both and kill them. Honestly you could say the entire planet of Korriban is this trope.
This actually costs Matt Engarde his case in Phoenix Wright: Ace Attorney: Justice For All. Having arranged for an assassin to kill his rival and frame his own manager for it, Engarde just can't resist trying to blackmail the assassin. Problem: the assassin has a very strong sense of honor. When informed he's being betrayed, he vows to get his revenge on Engarde - who pleads guilty in the hopes that prison will save him.
And, in Investigations, this costs Manny Coachen his life. If he'd never tried to usurp the ringleader he was working for, Alba would probably have left him to his affairs.
Also in Investigations, there is Calisto Yew. She herself acknowledges this in her own words, "I was destined to betray everyone from the very beginning." She betrays her own Yatagarasu members because she was a mole, Shi-Long Lang by revealing that she is a mole in Interpol as Shih-na, and while being taken away to be arrested she drops a valuable clue to betray her OWN BOSS.
Bitch in Sheep's Clothing Dahlia Hawthorne steals a two million dollar gem from her father, frames her first boyfriend for murder twice before getting him to kill himself, kills her stepsister, puts her cousin's boyfriend in a coma by trying to kill him, kills her second boyfriend, tries to kill her third boyfriend, puts her half sister in danger, tries to kill her other cousin, inadvertently causes the death of her aunt in the process, and locks her twin sister in a freezing and unstable cave to steal her identity and commit perjury in her name against her cousin. After admitting to all that, she claims that her mother is more evil than her.
She almost qualifies solely through the sheer number of times she betrayed Terry Fawles. The ways she betrayed him consisted of: convincing him to commit extortion and then letting him get arrested for it, possibly lying to him about who was in on the plot, probably pretending to love him back, being involved in getting him shot, letting him get blamed for kidnapping when it was consensual, framing him for murder twice and hiding the information that could get his death sentence cancelled, letting him mourn her when she was still alive, cheating him out of his cut of what they stole (or intending to), perjuring against him, (presumably) falsely accusing him of trying to kill her, giving him poison and instructions to drink it if a likely situation occurred (possibly without him knowing it was poison), and watching him drink it.
In one of the Dynasty Warriors games where one is allowed to create a custom character, the player can do quite a bit of this. Often one of the other two kingdoms' strategists will send you a letter asking you to defect to their side. Notably, this can happen repeatedly, and you can keep defecting as many times as you receive offers. Do this enough, and your character will gain the title of "The Hidden Blade," with a well deserved reputation for being reliably untrustworthy.
Also, see the section on Lu Bu in the Literature examples.
Similar to main games, Dynasty Warriors Online allows you to do this, but it's never called betrayal even by the game. You have a faction that you are part of for the game, you are assigned a general who gives you your pay and rank missions. If you go to a specific general each day and collect 2 months worth of stamps, you can get one stamp per day on a character, you can "reincarnate" and go to a different faction mid-war. You are treated as a new warrior to them rather than as a traitor to your old faction. if you made a habit of this you could probably go 4 different times per scenario. You don't get anything for doing this, though.
The Betrayal gamemode in Unreal Tournament III is CBD: The Game. Since the fraglimits tend to be high and the two most effective methods of garnering points is through backstabbing your teammates and gunning down said backstabber repeatedly, playing Betrayal is looking over your shoulder for teammates as well as enemies. Successful betrayals are also tallied up against your name on the scoreboard, and next to your name on the team roster, so everyone can see how much of a bastard you've been.
In Mass Effect, the krogan are a species whose homeworld bred them to be brutal, vicious, and straightforward, to the point that not only is treachery the norm, it's expected and understood. Having a "krannt" - a team of warriors who are loyal enough to you that they won't shoot you in the back - is a sign of a great leader.
Commander Shepard is on the receiving end of this, especially in Mass Effect 2. There are no fewer than three treacherous attempts to kill him/her in the first couple of hours of the game, Shepard saves Garrus from another betrayal, and the Illusive Man kinda-sorta betrays-by-not-warning-you with the Collector trap.
Shepard can become one of the kings/queens of this by the events of Mass Effect 3. You can backstab Samara, replacing her with her psycho daughter Morinth. Later, you can backstab Cerberus and the Illusive Man by destroying the Collector base. Then you can backstab the entire krogan species by sabotaging the genophage cure, which also involves backstabbing and killing both Wrex and Mordin. Then you can backstab either the geth or the quarians. Yes, Mass Effect 3 lets Shepard potentially betray and kill a species.
Depending on how you play the game, this can quite simply be a way of life in The Elder Scrolls. Whenever it may tickle your fancy (or, if you're playing Oblivion, whenever a character stops being important to the plot), you can sneak up behind the guy giving you your quest and backstab him. To death.
Even within the plot of Oblivion, there's a lot of backstabbing going on (literal and figurative). It gets downright ridiculous after a while, to the point that you can almost guarantee someone is going to backstab someone else or turn out to be a double agent before any given mission is over.
You get plenty of opportunities to be a backstabbing bastard in Dragon Age: Origins. You can betray Wynne in the "Broken Circle" Quest by agreeing with Cullen to purge the Tower, you can betray Kolghrim either by refusing to poison Andraste's Ashes with dragon blood or by poisoning the ashes to get the "Reaver" specialization then kill him afterwards, you can betray Zathrien or Witherfang at the climax of the "Nature of the Beast" Quest, you can betray Ignatio by deciding to kill him after completing the assassination contracts...it's a long list. All of these pale in comparison to the "A Paragon of Her Kind" Quest. If you play it a certain way both candidates for the throne will be confident that you will support him. You're free to choose whoever you want. If you've been performing tasks for one candidate there's nothing stopping you from picking his rival in the end.
Queen Anora can also do this to you twice! Once when you rescue her in Arl Howe's estate when you tell Sir Caulthren that you're here to rescue her and twice in the Landsmeet if you don't agree to get her to the throne.
This is essentially the goal of DEFCON, especially on the diplomacy game mode. Six players control shares of the world's supply of nuclear weapons, an on-screen timer lets you know when you can use them, you all start on the same team, and only one person can come first. You can be almost certain that at some point in the game every player will try to court every other player for an alliance, and every player will at some point attack every other player regardless of their past usefulness and / or loyalty.
Not an installment of Command & Conquer passes in the Tiberium setting without someone trying to betray either the Nod player or Kane. Its become tradition to expect at least one Starscream to rear their head during the Nod campaigns...
The Red Alert series's Soviet Union seems to live off of this trope (though this is a case of real life as well). Indeed, it was originally planned that in the Soviet campaign of RA 1 that a fight would break out between Stalin and Zukhov, and that a gun would get knocked to you - allowing you to decide who you were to betray.
The Resident Evil series gives us Albert Wesker, a man who seems to have betrayed every superior, subordinate, and partner he has ever worked with. Considering Resident Evil 5's revelation of Albert Wesker being an Unwitting Pawn in Spencer's plan to make himself a god, it's very likely that Spencer himself also qualifies under this trope, arguably even moreso than Wesker.
The Dragonball Z Budokai Tenkaichi What-if Saga The Plan to Conquer Earth's ending implied that the main villains (Broly, Mecha-Frieza, Bojack, Cooler, Baby Vegeta, and Super 17) intended to utilize this trope on each other.
In the first two games of the Geneforge series this is a viable option for the player due to the number of factions. It also makes an Omnicidal Neutral playthrough much easier if you can join a faction, loot their treasury, and simply walk into their leader's chambers before turning against them. Sadly, this is almost impossible in the later games.
Anyone with the Rebellious trait in Crusader Kings. Even if you can keep their loyalty going up, even if you support them with constant gifts, they will suffer random drops in loyalty to you, gain prestige gradually till they can claim your lands or even throne, and will eventually enforce those claims. And the worst part? If you put them back in their place, they'll probably revolt again, and give you the Realm Duress trait, making all your vassals like this. And if you do crush the rebel and take his titles, it upsets your other vassals... and you'll probably end up with them up in arms anyway.
Dane Vogul. Lets see, when he makes a deal with the Brotherhood to release their gang members from jail, he hijacks their weapon shipment after the gang members are killed by You. He had a partnership with the Ronin that he betrayed when they couldn't protect his company, and teamed with the Saints to let them take them out. And in the Ultor missions, he sends his personal hitsquad to wipe out the Saints. Then he blames it on the Board of Directors, allowing you to take them all out so he may take full command of Ultor. Then you kill him.
Tanya Winters in the first game. She betrays Tony Green for Warren Williams, Benjamin King for the both of them to rule the Vice Kings, and Warren himself so that she can take over by herself.
Bat betrays every person he works for in Digital Devil Saga. Not surprisingly, his demonic form is Camazotz, a demon of treachery from Mesoamerican myth.
Terry Higgins in True Crime New York City betrays the entire NYPD by faking his death, the four crime syndicates by having Marcus apprehend the leaders, pins the blame on Victor Navarro, his own boss, for the entire mess, and leaves Marcus when he refuses to join with him.
In Civilization IV, almost all leaders will never declare war against civilizations that they are on good terms with, and you can't even suggest it in negotiation. Almost all. Catherine the Great of Russia is unique - if you bribe her sufficiently, she will attack her allies.
Xana in Dark Messiah encourages Sareth to be a backstabbing bastard at every opportunity. She even encourages him to betray her supposed master and Sareth's father the Demon Sovereign by suggesting that Sareth should claim the Skull of Shadow's power for himself and leave his father to rot in Sheogh. Ironically enough, Sareth can betray Xana by purifying himself, an act that will render her Deader Than Dead.
"Trusty" Patches from Dark Souls. The guy acts all buddy buddy with you only to try and outright murder you mere moments later so he can take your stuff. He does this exact routine to you twice in the game.
Captain Scarlett in the Borderlands 2 DLC Captain Scarlett's Pirate Booty. Her intro even outright says "Will absolutely stab you in the back." She's also completely upfront and honest about how she fully intends to backstab you once you've recovered the treasure. Which makes the fact that backstabs you before you both get the treasure all the more surprising.
Inverted in the Dead Space series. Over the course of 3 games, Isaac is backstabbed by no less than 5 different characters.
As mentioned above, the Trope Namer: The Last Days Of FOXHOUND, being a Metal Gear Solid-based webcomic, plays Ocelot's betrayal habit for laughs, explaining that he has an actual disease called Chronic Backstabbing Disorder and needs an inhaler-like device to suppress it temporarily. In the meantime, woe betide anyone who bends down to pick up a nickel in his presence (as Liquid found out).
It appears that the Defense Secretary, Jim Houseman suffers it too.
"Is there a federal hiring quota for you people or what?"
And "iz-no-longer-a-Jäger" Vole, who tried to kill one of his old masters and changed teams later.
Black Mage from 8-Bit Theater, an Ax CrazySociopathic Hero and member of the Light Warriors, suffers from both metaphorical and literal Chronic Backstabbing Disorder. Or rather, everyone around him suffers. Usually from a knife to the head. He betrays his allies whenever a chance opens up, usually only to enjoy making them suffer. It usually backfires on him soon afterwards as it did when he sucked up to the dragon Muffin. Black Mage is not minion material and will object violently to the suggestion.
Drizz'l (self-proclaimed new leader of the New Dark Warriors): "What do you think you're doing?" Black Mage: "I'd say I was joining the winning team, but that'd imply there existed a time when I wasn't on Team Evil."
Thief is screwing his teammates over even more regularly than Black Mage is, he just rarely join another team in the process.
In Sluggy Freelance, Dr. Schlock switches between helping the main characters, helping Hereti Corp, and just looking out for himself over half a dozen times. It gets to the point where Riff insists that Schlock roleplay betraying the gang, just to get it out of his system.
Dr. Ginny Smith, from Irregular Webcomic!'s Cliffhangers storyline. A secret agent from Russia who works for both the Nazis and the heroes depending on what suits her, and plays on the affections of both Indiana Jones stand-in Montana Jones and Nazi lackey Erwin. Although she usually comes through for the heroes, she has handed over incredibly powerful artifacts to all three sides, or at least tried, in the past. In the words of Monty himself, "She's a Russian triple agent working for the Nazis. You expect her to be consistent?"
Wrecking Paul from Everyday Heroes always works with female sidekicks since he's a serial killer who prefers women as his victims. If for some reason his preferred target doesn't show up, he'll turn on his teammate. This eventually leads to Iron Jane's Heel Face Turn.
Vriska of Homestuck has a pretty severe case of this. The other trolls have wisely learned to stay well away from her schemes.
Anthem in the Torture Lord's temple, having lost her sword again, uses Vish! as a weapon against the monsters and proclaims herself this:
Anthem: Never let it be said cowardice and betrayal ever led me wrong.
Quite common in Survivor: Fan Characters, being based off Survivor. Baxter from Season 3 is the most prominent example of this trope, having gone mad with power and then backstabbed approximately five people, some in direct succession, in order to get to the finals. Unfortunately, four of the people he backstabbed happen to have been on the jury, and three of them vote for someone else who didn't backstab them, Montana, ultimately losing him the game.
It's starting to look like Nale of The Order of the Stick has a case of backstabbing disorder. The jury's still out on whether he works for the fiends, Xykon, his father, or himself.
Oh, he definitely works for himself. He only works for Xykon and Tarquin when it's convenient (and when it keeps him alive), and as for the Fiends, he doesn't even know about them — he's being manipulated by them, via Sabine and Qarr.
Tarquin is definitely this. Be the power behind the throne, when people hate the power, start a revolution, aided by other kingdoms secretly run by his buddies, become the power behind the new throne, rinse and repeat for all three involved kingdoms! All that matters is Tarquin is in charge.
Tech Infantry has Andrea Treschi, who starts out as a Federation officer, retires and joins a criminal gang, kills the leader of the criminal gang and takes over, gets drafted back into military service, and promptly assassinates his former commanding officer. Then he contacts the biggest group of rebels currently fighting the Federation and agrees to find and retrieve a disgraced former politician and bring him back to launch a political coup. He succeeds, but the politician gets assassinated by a rival faction and the coup fizzles. So Treschi flees to a neighboring star nation and offers his services, and helps them set up The Plan that leads to their conquest of the Federation after a civil war followed by alien invasion severely weakens it. Treschi becomes the right-hand man of the new Emperor, then orchestrates some elaborate court intrigue to ensure his puppet prince takes over when the Emperor dies, and Treschi becomes the true power behind the throne.
Agent South of Red vs. Blue is revealed to suffer from this. It's apparently a survival reflex.
Sahar, of the Whateley Universe. She started out backstabbing as an orphan in Beirut, and then got superpowers. At Whateley Academy she went from clique to clique, picking a target, backstabbing, getting a copy of said target's powers, and then moving on. Even the Alphas fear her. She doesn't betray a target to join with the new one. She just betrays a target so she can start over, finding a new power to copy! Best one was when she pulled this trick to a guy AND his girlfriend!
Ironically, she pulled a heel face turn before the series started, and attempts to redeem herself.
Javelin Whitetail on M3, having defected from numerous factions over the years. It took a while for some characters to clue in on the notion that she should not be trusted. Repeated betrayals is a staple of the MUSH.
Wario's loyalty in There Will Be Brawl is to money, power and survival, and he is willing to backstab and use anyone to get and/or keep it. This is a guy that used his mentally challenged brother to kill a kid because said kid was a Pokémon trainer.
Darth Apparatus in The Gungan Council has betrayed every faction he's been a part of at least once in some way. Bonus points for people still wanting to be his ally at times.
Re Boot's Megabyte suffered from Chronic Backstabbing Disorder and was brave enough to admit it. "I doublecross whomever I please." Good for you, Megabyte. You know, the first step to recovery is admitting there is a problem.
And his "physiological" cousin, Protoform X (Rampage) had to be locked up because he was chronically treacherous.
Not so much treacherous as an unstoppable, immortal, psychopathic, cannibalistic monster who was going to be left on a distant asteroid simply because the Maximals had no way of killing him. He's never claimed to be loyal to anyone bar himself.
While we're on the subject of Beast Wars, we should also include Tarantulus and Black Arachnia, who spent most of the series making attempts to backstab either Megatron, each other, or both at once.
Starscream in Animated is working on it. Unfortunately, Megatron is a good bit smarter this time.
Prime provides an interesting twist: 'Scream only gets stabby if he thinks he can get away with it — if he thinks Megaton won't ever find out. The rest of the time ...
Airrachnid, on the other hand, is a bit more brazen in her betrayals.
And sided with the heroes in the same show is Raimundo. Due to being constantly ignored, belittled, and unappreciated, he eventually betrayed the Xiaolin monks to help Wuya (who, ironically enough, fully kept up her side of the bargain). He eventually turns on Wuya to save his former comrades, and reduces Wuya back to a spirit. Then in a much later episode, Raimundo pretends to betray the monks again to side with Hannibal Bean as part of a Batman Gambit so he could bet Bean's Shen Gong Wu, raise the ante, then backstab Bean by throwing the match so the Xiaolin monks would get what was bet.
Bender from Futurama will switch sides whenever he feels like it, if there is something in it for him, that is. In the DVD movie Into the Wild Green Yonder he helps Zapp Brannigan capture Leela because her eco-terrorism is threatening to overtake his crime track record. After helping to send her to prison, he busts her out, committing 15 felonies in the process thus retaining his title.
Darkseid is just as untrustworthy in the DCAU as he is in the comics, which he demonstrates in one episode. First he convinces the Justice League to help him fight off Brainiac's invasion of Apokolips. Then he betrays Superman to Brainiac in exchange for Apokolips' safety. Then Darkseid betrays Brainiac by using a Mother Box to take control of him in a bid to discover the Anti-Life Equation and rewrite the universe. This left an impression on Brainiac — in a later episode, Brainiac was reluctant to make a mutually beneficial deal with Luthor because his experiences with Darkseid taught him that organic beings couldn't be trusted.
On Wacky Races, Muttley was known to bite the hand that feeds him (a.k.a. Dick Dastardly), but in "Race To Racine" he pulls a doozy. In a sabotage attempt, Dastardly plants him among the Ant Hill Mob, who take him as one of their own (Smiley O'Toole). Clyde instructs him to take Dastardly out, of which Muttley first surprised says "Who, me??" But then he gets a shit-eating grin on his face, snickers, runs atop the Mob car and fires a hand grenade at the Mean Machine.
Dastardly: (emerging from the smoldering wreckage) And after giving him the worst years of my life...where did I go wrong??
Heather from Total Drama. the only way Heather got to the final rounds more than once was through this. however, it's also been known to backfire on her and has done so twice. Lindsay and Beth, two victims of Heather's abuse still won't associate with her after season 1. she also failed this in season 3, having her hands on the money for all of three seconds before losing it and ending up with nothing.