Manchurian Agent

Memory Gambit and Neuro Vault meet Deep Cover Agent. A person is Brainwashed so that, on a certain trigger (either a situation, or else a phrase only someone in the know would ever say), they will go from their normal self to The Mole; they will most often remember nothing afterward.

See also Brainwashed, Berserk Button, Morality Dial, Tomato in The Mirror, Conveniently Unverifiable Cover Story and Lotus Eater Machine. Compare Memory Gambit, which is when you do this to yourself. May require Deprogramming to cure.

Anime and Manga

 * Lost Brain pulls this one.
 * Tengen Toppa Gurren Lagann has.
 * Happens in Naruto Shippuden with Sasori's spies ( and  .)
 * in Gundam 00. In this case, the trigger is the presence of a particular person:
 * from Noir. She was an incredibly awesome assassin before. Fear what she became.
 * Lelouch's mind-controlling Evil Eye lets him give people orders that cannot be refused, and in addition to the immediate Brainwashed victims, he can also create a Manchurian Agent by applying special conditions to the command. For example, he made a Britannian officer into a Manchurian agent that would see him as  when he grabbed his collar.
 * Covered by the one-off character of Twyla in Voltron.
 * in Doubt
 * Occurs in Mahou Sensei Negima with . In this case, it seems to simply be a decoy to keep Ala Alba from noticing something particular, but Mana notes that they can't rule out the possibility of a Trigger Phrase.
 * In Tantei Gakuen Q, Pluto/Meiousei does this all the time to its clients and its own agents as a failsafe - on the trigger, they'll kill witnesses, or themselves, or go insane... and it's not pretty.
 * In Death Note,  acts as a Manchurian Agent on behalf of  . One of the most ingenious plot twists in a series full of plot twists.
 * Dance in The Vampire Bund provides the nanotechnology known as the "Pied Piper" which when applied to vampires forces their mind to register any orders they receive as coming directly from their overlord ("Release the insane werewolf and lock down your HQ so you are trapped with it? Of course My Liege").

Comic Books

 * In Assassin's Creed the Fall, serves this role in 's Xanatos Roulette to weed out the Assassin Order.
 * Blue Beetle, in a memorable and bloody couple of issues of Justice League International; they ultimately had to resort to a Journey to The Center of The Mind to get him deprogrammed.
 * Titans/Flash supporting character Frances Kane was originally programmed this way by her therapist, probably contributing to her later mental problems.
 * In the comic book One Hundred Bullets, the phrase (used to cause old memories to re-emerge rather than force them to do something against their will) is "Croatoa."
 * Subverted in an issue of Justice League Adventures, where this is attempted against the subject's will, but whoever it was made the mistake of choosing The Question as their mole. He's so paranoid, he actually found himself out before he could do any damage.
 * These turn out to be central to the plot of Hondo-City Justice - a large number of girls with alien DNA are triggered to kill the drokk out of any Yakuza members they happen to see. Asahara manages to overcome it.
 * In the conclusion of the Daredevil "Shadowlands" event,  was revealed to be Kingpin's Manchurian Agent.
 * Inverted in the Marvel Transformers comics when Ratchet, forced by Megatron to rebuild Starscream as a Pretender, hides Starscream's true personality deep in his neural circuits. Megatron then sends the "new" Starscream against the Autobots and Decepticons on Earth. One shot from Hot Rod damages Starscream, and he immediately reverts to the Dirty Coward we all know and love.

Film

 * The near-eponymous (technically speaking, the Manchurian Agent isn't the "Manchurian Candidate", but that's nitpicking) The Manchurian Candidate (The Film of the Book). There are currently two adaptations, the 1962 adaptation and the 2004 adaptation.
 * Total Recall.
 * Arguably, the entire population of The Matrix, being as how anyone who hasn't been freed from the Matrix can become an Agent at any time. It's arguable because, while the result is the same, from the perspective of anyone inside the Matrix they physically turn into an Agent.
 * In the movie Zoolander, the title character is hypnotized into becoming a berserk assassin when he hears the song "Relax" by Frankie Goes to Hollywood.
 * More or less the entire point of the move Curse of the Jade Scorpion. One of the key words was "Madagascar". Bonus points in that one of the people thus hypnotized was the detective in charge of his own investigation, and doesn't realize it.
 * Telefon (1977). The KGB plant 51 such agents with fake identities in the United States, programmed to commit acts of sabotage on receiving a Trigger Phrase. Unfortunately a fanatical Stalinist opposed to détente steals the list of agents, and the Soviets have to sent Charles Bronson to stop him.
 * was his own Manchurian Agent in the movie Cypher.
 * was one in The Naked Gun.
 * Going Berserk - John Candy's character is brainwashed by a cult to assassinate his fiancée's congressman father using a playing card as a trigger. Something goes wrong in the hypnotism though, and the trigger doesn't make him a cold-blooded assassin as much as a loud obnoxious asshole - Hilarity Ensues.

Literature

 * In the fourth A Series of Unfortunate Events book,
 * In David Wingrove's Chung Kuo, a servant is made to attack General Tolonen
 * Richard Condon's The Manchurian Candidate. The Trope Namer.
 * In Frank Herbert's Dune, the Bene Gesserit can use psychosexual conditioning techniques (called hypno-ligation) to control people. They can trigger their victims by using code words.
 * The ghola Hayt has a trigger word that is intended to trigger an assassination. His ability to resist it becomes something of a plot point.
 * Dean Koontz' Night Chills has an entire town of sleepers triggered by the phrase "I am the key".
 * In the Star Wars Expanded Universe, one of the X-Wing books used this. The trigger phrase, different for each agent, was a nonsensical problem (for example, "Those Wookiees are dancing in the parlor again") that instantly became the sole focus of the brainwashed person's life - and the only way to "solve the problem" was to carry out the preprogrammed mission, usually an assassination.
 * An earlier X-Wing book had a version not triggered by a code phrase, caused by long-term torture and reconditioning in the Lusankya prison. These agents would be unaware of what Isard had done until they were triggered, at which point they became Apologetic Adversaries. The example above was considered more dangerous because it could be engineered by only a day's worth of chemical treatments after kidnapping the target, and it also managed to stir up Fantastic Racism by, for example, causing a fleetwide suspension on Twi'lek pilots.
 * The Ipcress File.
 * Imriel in Kushiel's Mercy: the trigger is kissing his beloved.
 * Lord Byron was almost used as one of these in Tim Powers' The Anubis Gates.
 * Inverted in the Lord Darcy story A Case Of Identity, where is a homicidal maniac when in his natural state, but has been constrained by mental healers' geas effects to be entirely harmless and trustworthy.
 * The Glass Books of the Dream Eaters features a trigger phrase known only to the highest echelon of the Cabal, used on those who have undergone the Process, that makes them It varies based on several factors; it includes a colour ("blue" for those who underwent the Process at the Institute, "orange" for those who underwent it at Harschmort,) a Biblical reference ("Magdalene" for the recruited followers, "Caesar" for the officers, etc.,) the place they were recruited ("Royale" for the Hotel Royale, "Regiment" for the army,) and the words "ice consumption." So, for example, the Countess uses "orange Magdalene orange Royale ice consumption" on
 * In the Captain Underpants books, Mr. Krupp turns into Captain Underpants when he hears fingers snapping, and returns to normal when water is poured on his head.
 * Programming people is routine for protagonist's agency in Oleg Divov's Brothers in Reason. as well as  are programmed to shoot  on sight, one with a gun and the other with a laser implanted in the forearm. The first one is revealed when he begins to suspect something and asks his half-brother to hypnotize him. When he becomes aware of the programming, he is now free to disobey it.
 * It is standard policy for all agency employees to undergo brainwashing whenever a mole is suspected.
 * This is the same agency that psychically zombifies the entire population of Earth into loving everything Russian, the ultimate psychotronic weapon.
 * In the Shadowrun novel Night's Pawn, a Mega Corp executive's daughter is programmed to kill her father as soon as they're alone together. Worse, she's programmed to do so with a concealed bone spur that can't be detected on scans ... and that's designed to slit her own arteries as it emerges, causing her to bleed to death and thus be unable to explain what happened to her.
 * In The Dresden Files novel Turn Coat, there are abounding fears within the White Council of Wizards that there are traitors running amok after one of the Senior Council is murdered. It turns out that someone has been mucking with the heads of  On top of that,

Live Action Television
"Adelle DeWitt: There are three flowers in a vase. The third flower is green."
 * Several episodes of The Wild Wild West.
 * Firefly's River Tam, although it's only really seen in The Movie, Serenity. Her trigger was a subliminal message buried in a Fruity Oaty Bars commercial, which caused her to go into martial-arts-killing-machine mode.
 * in Babylon 5, in season 4.
 * Spike in season seven of Buffy the Vampire Slayer. The trigger is "Early One Morning," a song his mother used to sing when he was a child.
 * The Romulans do this to LaForge in the Star Trek the Next Generation episode "The Mind's Eye".
 * In the Star Trek Deep Space Nine episode "Inquisition", Bashir is accused of being one of these
 * This is the setup for My Own Worst Enemy, which features one.
 * This is an inversion, though, as Edward Albright, the spy, is the original personality, and Henry Spivey, a quiet middle-management office employee with a wife and two kids, is the implanted cover.
 * The whole premise of the show is the breakdown of the chip that separates the two lives and Henry becoming aware of his alter-ego. Cue the inexperienced Henry going on missions, and Edward sleeping with Henry's wife.
 * This was a favourite tactic of the aliens in the 1970s British sci-fi series UFO.
 * A couple episodes of Stargate SG-1 use this.
 * Done twice in the MacGyver episode "Brainwashed." Jack Dalton and Pete Thornton are both programmed with different code phrases buried in the speech to be given by the president of a fictional African country they're programmed to assassinate. The simultaneous missing weekend over which they were programmed is covered by Fake Memories.
 * In Big Wolf On Campus, the Evil Werewolf Syndicate try to increase their numbers by doing this to Tommy; whenever he hears the code phrase he's supposed to bite the nearest person.
 * The alien "sleeper agents" on Torchwood.
 * Also in the episode "They Keep Killing Suzie", where a certain someone  encodes multiple triggers into a hapless man she met at a philosophical group.
 * in Dollhouse.

"Silence: You should kill us all on sight."
 * The episode "Attack Angels" of Charlies Angels features a villain who runs a business creating examples of this trope and selling their services to other villains.
 * from the 2000s Battlestar Galactica.
 * Rocko from Puppets Who Kill was brainwashed into becoming an assassin for the government in one episode. The trigger to switch him between normal and brainwashed was to show him a Jack of Diamonds. Naturally, this led to a whole bunch of stuff happening that made the two scientists stop and note that they shouldn't have used something as common as playing cards for the trigger.
 * Get Smart - Max is abducted and brainwashed to assassinate the Chief over their usual chess game at the club - an employee is the KAOS agent behind the scheme and knows the Chief always wins, so he makes "Checkmate" the trigger. It's Get Smart-- of course it doesn't work as planned.
 * Derren Brown's special "The Heist" was a real-life attempt at creating four of these.
 * In case you're wondering...
 * In his The Events special, he picks a susceptible person in a cafe and then programs the guy to steal a TV when he sees a girl wearing red and holding a balloon. The guy does and then tries to come up with a lame excuse for his behavior when caught.
 * He goes even further in the special "The Assassin". He picks a susceptible person from his audience and then spends some time programming him to respond to the polka dot pattern (which puts him into a susceptible trance after which he doesn't remember anything) and a specific ringtone (that causes him to think he's still at the shooting range firing at a target). The only other thing that is required is someone to tell him who the target is. In this case, it's Stephen Fry. . Derren keeps referring back to the assassination of Bobby Kennedy, whose killer Sirhan Sirhan has been claiming for decades that he's been programmed by the CIA.
 * The Mission Impossible episode "Mindbend".
 * The Vega$ episode "Lost Monday" has Binzer being hypnotized into constructing and detonating a bomb. The hypnotist instructs him to respond to the trigger word "superstar".
 * In the Farscape episode "A Prefect Murder", Aeryn is turned into one via a mind-controlling bug. There's also a subversion: after being bitten. John pieces together what's happening just in time to hand over his weapon and leave the area.
 * An episode of The Outer Limits deals with a prep school which is a front for an agency training these. It is revealed at the end that their "recruits" have infiltrated many agencies, including law enforcement. Programming is done with an implanted computer chip, although it fails with someone who has ulcers due to a treatment formerly prescribed for it.
 * In the (original) TV series of V, Ham Tyler is brainwashed to kill resistance leader Michael Donovan.
 * In one episode of In Security, N'udu is brainwashed and assigned to kill his best friend.
 * The entire human race becomes one in Doctor Who. The Silence's ability to control humanity via post-hypnotic suggestion ends up accidentally backfiring in the most spectacular way possible when one of them is recorded accidentally uttering the following words, which is then broadcast to the whole planet during the Moon-landing.

Video Games

 * In Bio Shock,  Slightly different than most, in that it didn't put him into any kind of trance, it just made him decide that's what must be done. The details on how exactly it works are somewhat lost, as
 * Kilrathi defector "Hobbes" was revealed as one of these in Wing Commander 3: Heart of the Tiger, with the trigger phrase... "Heart of the Tiger".
 * in Tales of the Abyss, who was programmed to when he heard the trigger phrase.
 * in Psychonauts apparently had some sort of subliminal trigger implanted in his already fragmented mind by the Big Bad. When  released that trigger while exploring his mind, he followed those implanted orders to destroy the asylum and cover up anything that went on there.
 * from Final Fantasy VII probably counts.
 * in Call of Duty: Black Ops is programmed to . It's not outright stated whether this succeeded or not, but it's heavily implied.


 * In an overheard conversation in Assassin's Creed Revelations, the Templars have in the past used brainwashed spies against the Assassins. Shaun Hastings suspects that, but there are hints that

Visual Novel

 * In Fate Stay Night, asking too much about Caster will trigger a bad end.

Webcomics

 * Oasis from Sluggy Freelance.
 * Unlike the common zombie-like revenants in Girl Genius, the revenants from Sturmhalten appear exactly like normal people (well, as normal as anyone in a Phil Foglio comic) until their controller issues them orders, which they carry out against their will. Interestingly, some are capable of freedom within those constraints. (Such as killing a friend so he won't suffer a Fate Worse than Death.)
 * Recently, Tarvek stated that the zombie revenants are actually only, "A statistical extreme," and that the sleeper agent revenants are actually far more common. It's just that, since the zombie revenants are far more obvious, they managed to divert attention from the real things.
 * Gabriel (of Penny Arcade fame) is responsible for the murder of the president of the U.S.A in one comic after presumably having the instruction planted in him after going to a psychotherapist (or something).
 * in Darths and Droids.

Web Original

 * In the Whateley Universe, Team Kimba have worked out that Solange has created a Manchurian Agent among their friends. They still don't know who it is, but they're sure the agent has planted a blackmail note for Solange, and put a tracker in Fey's luggage.

Western Animation
": Time to blow up the clown.
 * Haley in an episode of American Dad. The trigger phrase? "I'm getting fed up with this orgasm!"
 * Another episode had Steve react to a trigger that compelled him to assassinate a certain government official, as a throwaway gag.
 * Using this, Sideshow Bob turned  into a Laser Guided Tykebomb in one episode of The Simpsons.

Homer: Go. Blow."


 * Inspector Gadget did this once, with a game show that hypnotized its contestants (including the titular character) into reacting to the phrase "Going my way?" Turns out it did make him go their way...
 * The brainwashing done by Dai Li in Avatar: The Last Airbender is activated by saying "(name), the Earth King has invited you to Lake Laogai." to which they respond by gaining Mind Control Eyes and saying "I am honored to accept his invitation."
 * The Adventures of Jimmy Neutron in My Big Fat Spy Wedding, where Jet Fusion is hynotized to kill anyone who says "I have the Ring". The catch? Jimmy is the Best Man in the wedding of Jet Fusion and Beautiful Georgeous. Crowning Moment of Funny? I think so.
 * Mayor Adam West of Family Guy is a deep cover agent who is activated by the phrase "Boy, that Italian family in the next table sure is quiet." Also,
 * Bonus points for doing this to a character whose.
 * Luna Fatale in the animated series of ''Spirou and Fantasio".
 * Often discussed in Young Justice. Since Superboy is a clone from Cadmus, many were fearful that he's secretly programmed to spy and/or turn on the Justice League and their affiliates.