%% Zero Context Examples are not allowed on wiki pages and have been commented out. Don't uncomment them without providing context.
%% The list is alphabetised. Please add new examples accordingly.
* ''Series/TwentyFour'': This show has probably the most famous example of this. Over the course of eight seasons, there have been ''fifteen'' named and confirmed moles, not counting the [[spoiler: hundreds of unnamed ones in Day 7]]. This figure also doesn't include double and ''triple'' moles. Amazingly, even by the eighth season, the characters are still astounded when a mole within CTU is uncovered. This has prompted many fans to suggest that Jack Bauer needs to have a [[JackBauerInterrogationTechnique long talk]] with CTU's director of Human Resources. Not just CTU itself, every agency in the series is plagued by numerous moles.
* ''Series/TheAdventureGame'': After appearing as a contestant in the last episode of the first series, former ''Series/BluePeter'' presenter Lesley Judd appeared as The Mole in the second series, ostensibly needing to be rescued by the three contestants but actually working to hinder them. The contestants would be told in advance that "one of [them]" was a mole, and around two-thirds of the way through each episode, they and Judd would be gathered together and asked to collectively identify the mole; if they guessed correctly, Judd would confess and allow them to continue, but if they guessed incorrectly, the falsely accused mole would be eliminated from the team (though this came with the blessing of exempting them from the episode's final game, the Vortex), Judd would unmask herself, and the remaining two contestants would have to continue on their own. [[spoiler:Only one of the five teams from Series 2 (comprising mathematician and Rubik's Cube expert David Singmaster, ''Nationwide'' presenter Sue Cook, and marketing executive Philip Sheppard) correctly identified Judd as the mole.]]
* ''Series/AgentsOfSHIELD'' reveals multiple moles in "Turn, Turn, Turn": [[spoiler:HYDRA has so thoroughly infiltrated S.H.I.E.L.D. that they are able to stage a coup, capturing multiple S.H.I.E.L.D. facilities. In addition, Agent Garrett turns out to be the Clairvoyant and a HYDRA operative, and Agent Ward turns out to be his right-hand man.]] Later in Season 2 Episode 3 "Making Friends and Influencing People" it is revealed [[spoiler: Agent Simmons is undercover in HYDRA, leaking their projects to Coulson]] and in Episode 5 "A Hen In The Wolf House" [[spoiler: Bobbi Morse A.K.A Mockingbird, Head of Security for HYDRA is also a mole...put in charge of finding moles.]]
%%* ''Series/{{Alias}}'': Has done this.
* ''Series/{{Angel}}'': Cordelia is like this in Season 4, although it isn't the real Cordelia as her body is being used by an antagonist higher power of [[TotalitarianUtilitarian ambiguous morality]].
* ''Series/ArrestedDevelopment'': Spoofed, when Tobias is asked to be a mole for the CIA; he think it's a casting agency, and assumes they want him to put on a mole costume.
* In the ''Series/{{Arrow}}'' episode [[Recap/ArrowS5E7Vigilante "Vigilante"]], Artemis is revealed to be a mole in Team Arrow for Prometheus.
* ''Series/AshesToAshes'': It is revealed near the end of season 2 that [[spoiler: Chris]] has been blackmailed into being a mole. He is however not a bad guy, so he redeems himself promptly with a FaceHeelTurn.
* ''Series/TheAssets'' is the true story of Aldrich Ames, a CIA agent who was a mole for the KGB for years.
* ''Series/BabylonFive'':
** A couple of examples turn up:
** At the end of the first season, Garibaldi uncovers a plot to assassinate the president of the Earth Alliance. Before he can deliver a warning, he is shot in the back by [[spoiler: his aide Jack]].
** In "Divided Loyalties", Lyta Alexander delivers a warning that someone on the station has a deep-cover personality implanted by Psi Corps. [[spoiler: It turns out to be Talia Winters.]]
* A minor example in one episode of ''Series/BarneyMiller'' has the squad looking a "field agent" who is working for InternalAffairs. Due to the litany of excessively trivial offenses they're cited with, they quickly figure out that it's Levitt.
* ''Series/BattlestarGalactica2003'': Played with. From the beginning of the first season the audience is aware that Boomer is a Cylon, although the crew of the ship, and Boomer herself, are not. The [[StoryArc season arc]] features her struggling with self-doubt over whether or not she's human, attempting suicide, and ultimately learning that she is in fact a Cylon. In the season finale, she seemingly sides against her kind and sets off a nuke destroying a Base Star full of other copies of her, and at that moment [[WhamEpisode the Wham]] hits; [[spoiler:as Commander Adama is meeting her in CIC and praising her for a job well done, she draws her sidearm and shoots him twice, point blank, in the chest.]] The reveal of several other characters in the season three finale includes [[spoiler: two significant moles, as well as two lower tier individuals.]] [[spoiler: Not really moles though -- their presence in the fleet turns out to be more like a punishment -- or a joke.]]
* ''Series/{{Blackadder}} Goes Forth'': One episode has Blackadder look for a mole within the military hospital. He takes the opportunity to torture...I mean interrogate Darling for kicks, and gets cozy with the hospital nurse, while a man with an obvious German accent is a patient in the hospital. Come to find out in the conclusion, though, the nurse was the actual mole, and the 'German spy' was, to Darling's embarrassment, a ''British'' mole who picked up an accent during his time in Germany. [[spoiler: Then the TwistEnding reveals that ''George'' was inadvertently the mole, writing letters to his German uncle.]]
* ''Series/{{Blindspot}}'':
** Jane's handlers in [[NebulousEvilOrganization Sandstorm]] force her to be this for them in the FBI throughout Season 1, under threat against Kurt's life.
** Throughout the first half of Season 2, it is repeatedly mentioned that Sandstorm has a second mole, meant to monitor Jane in case she defects. The midseason finale reveals it to be [[spoiler: Dr. Borden]].
* ''Series/{{Bones}}'': [[spoiler:Zack Addy is one for the Gormagon. He comes back occasionally, though, because he's a freakin' ''genius'' and]] nobody else can figure out the killer.
%%* ''Series/BreakoutKings'': [[spoiler: U.S. Marshal Colburn]] is revealed as one in "Where in the World is Carmen Vega?".
* ''Series/BuffyTheVampireSlayer'': Shows up a few times.
** Jenny was sent to Sunnydale in Season 1 to keep an eye on Angel.
** After Buffy joins the Initiative, she considers herself still to be investigating them and not really a member.
** Spike is a mole inside the Scoobies, for Adam.
** Riley in [[ComicBook/BuffyTheVampireSlayer Season 8]] is a ReverseMole on Buffy's side.
* ''Series/TheCloser'': In the final season, a leak in Chief Brenda Leigh Johnson's department traces back to [[spoiler: Lieutenant Gabriel's girlfriend Ann. Goldman hired her to cozy up to Gabriel for inside information about the LAPD and Brenda's cases especially. Gabriel is legally cleared of wrongdoing, since everything he shared with Ann was said in confidence. He's still heavily scorned by members of the team for his accidental role in the leak.]]
%%* ''Series/{{CSI}}'': [[spoiler: Undersheriff [=McKeen=]]], revealed in the final episode of season 8 in spectacular fashion.
* ''Series/DoctorWho'':
** [[Recap/DoctorWhoS5E5TheWebOfFear "The Web of Fear"]] concerns the fact that one character in the group is working for the Great Intelligence. Oddly for anyone who knows anything about ''Doctor Who'', the character clearly intended to be the primary suspect for most of the story is (then-)Colonel Lethbridge-Stewart. (The novelisation alters this by clearing him of suspicion early on.) The viewer's primary suspect is probably Chorley. The actual suspect turns out to be [[spoiler: Arnold, a MauveShirt who got killed in an earlier episode and is [[TheUndead still moving around as a possessed corpse]].]]
** In [[Recap/DoctorWhoS14E1TheMasqueOfMandragora "The Masque of Mandragora"]], Sarah Jane is hypnotized into doing this.
** The character of Vislor Turlough is initially introduced as a mole character who orchestrates his way into becoming one of the Fifth Doctor's companions under orders from the Black Guardian to kill him, but eventually does a HeelFaceTurn and defies the Guardian and goes on to become a loyal companion for the rest of his time on the show.
** In a heroic example, the alternate-universe Pete Tyler is revealed to be a spy inside Cybus Industries, anonymously sending information to [[LaResistance the Preachers.]]
** In [[Recap/DoctorWho2006CSTheRunawayBride "The Runaway Bride"]], Lance -- the fiancé of the eponymous bride -- is revealed to be working for the sinister Empress of the Racnoss.
** In [[Recap/DoctorWhoS29E13LastOfTheTimeLords "Last of the Time Lords"]], [[spoiler:a scientist Martha gets help from turns her over to the Master. It's an example of an ExploitedTrope however, Martha's actually counting on her doing so as part of her plan.]]
* ''{{Series/Dollhouse}}'': The early episodes set up that there's a spy somewhere in the House, eventually revealing it to be [[spoiler: head of security Dominic]]. Notable in how the character was practically the only one fans ''hadn't'' suggested The Mole to be...''because it was such an [[DevilInPlainSight obvious choice]], assumed that it ruled them out.'' Oh, Joss Whedon, you insane genius. In the final episodes it is revealed that in fact [[spoiler:Boyd]], a trusted figure in Adelle's house, was the one in charge of Rossum Corporation.
* In ''Series/{{Dominion}}'', the humans now face a serious threat of this from [[EliteMooks the Powers]], who don't need to possess human hosts, and can thereby get past the angelic detection equipment. And then there's the [[LesCollaborateurs Black Acolytes]], the cult that worships [[BigBad Gabriel]], and are far reached enough that one of them is [[spoiler: William Whele, leader of the [[FantasticReligiousWeirdness Church of the Savior]] and son of the second most powerful person in Vega.]]
* ''Series/{{Firefly}}'': Yolanda/Saffron/Bridget made a living out of being The Mole. She was introduced as an innocent and submissive young woman. She claimed she's a reward as wife for their captain because her people couldn't pay them in a standard way [[spoiler:while in fact she's a trained companion and criminal mastermind who tried to kill the crew in order to sell their ship. She also ratted out her husband who loved her deeply and thought she was kidnapped from him.]]
* ''Series/{{Flashpoint}}'' has a couple, though not in the SRU itself.
** In "Clean Hands", a serial killer is transported following extradition. Among his victims were the daughter of airport employee Walter Volcek and the sister of customs agent Delia Semple; Semple and Volcek team up to take him out. Volcek is caught and stopped, but if it weren't for an offhand comment Sam happened to drop and Parker happened to pick up on, the SRU wouldn't have caught on to Semple until it was too late.
** In "No Promises", Spike's mentor becomes this out of desperation (he needs money to save his drug-addicted daughter). When he starts backing down, his daughter is kidnapped and held hostage, forcing him to go along with their plans.
** "Just a Man": Ed Lane suspects that Anton Burrows is this, pretending to be helping while actually misleading him. He turns out to be wrong, however; Burrows risks his own life to protect the very people who had prevented him from getting parole the same day.
** Two of the apparent hostages in "Grounded" are actually in on the plot. The two main hijackers do reveal that they have accomplices posing as hostage passengers, but they don't tell the passengers ''who'' they are. It's not until about halfway through the episode that the third conspirator reveals herself, and it's several minutes more before she orders the final member of the team to reveal himself because they need the extra hands.
* ''Series/GameOfThrones'': Locke poses as a Night's Watch recruit to find Bran and Rickon, going so far as to actually take the vows. He's killed before we find out how he was planning to get out of that.
* ''Series/{{Glee}}'': Quinn, Santana and Brittany, the three Cheerios who join Glee Club, are secretly spying for Cheerios coach Sue Sylvester, who is trying to bring down the club. As the series goes on, though, and Quinn's popularity and [[spoiler: membership in the Cheerios]] are destroyed by her pregnancy, [[HeelFaceTurn this gradually changes]].
* ''Series/{{Greek}}'': Jen K is a mole for the school newspaper, and puts a dent in the entire Greek system with her article. Apropos that Jen K is played by Jessica Rose of ''WebVideo/Lonelygirl15'' fame (see below).
* ''Series/HoratioHornblower'':
** Sailor [[spoiler:Wolfe]] seemed to be an ordinary seaman who joined HMS ''Hotspur'' by mere chance because he just wanted to serve in the Royal British Navy. [[spoiler:He's an Irish rebel who collaborates with Napoleon Bonaparte, trying to liberate Ireland from the Brits by invasion and war.]]
** [[spoiler:Captain Hammond]] was mentioned by name in several episodes and appeared in all three instalments, but he never looked to be a significant character, other than he was a rather famous figure in the Navy and a HangingJudge during a court-martial in "Retribution". In "Loaylty", it's revealed that he was [[spoiler:secretly working for Irish rebels his whole life.]]
* Vera from ''Series/HouseOfAnubis'', in an interesting EvilVersusEvil version, where she was pretending to like and work for Victor, when she was really on Rufus' team. However, she may have wound up BecomingTheMask by the end of the season. That didn't stop Victor from kicking her out when he learned the truth.
** Fabian's godfather Jasper fell into this trope, as he was being blackmailed by Vera herself, making him spy on his own godson and his friends. Fabian was heartbroken upon finding out, but knew Jasper was doing it to ''protect'' him from Rufus.
** Jerome, who was also working for Rufus in the first season, was using Alfie to get information and artifacts from the Sibunas. Alfie eventually stood up to him, refusing to spy on his friends. Jerome later becomes a ReverseMole and tries to get information from Rufus to give to Sibuna.
** Early in the third season, Fabian and Patricia ''thought'' KT and Eddie were working for Victor and caused Nina's disappearance, similar to how Patricia [[CallBack thought the same of Nina earlier.]] The two of them were isolated from Sibuna for a little bit until they finally learned that their friends were trustworthy.
%%* ''{{Intelligence}}'': Half the cast is, at any given time, a mole for one or more members of the rest of the cast.
* ''Series/{{JAG}}'':
** In "War Cries", [[spoiler: the boy, his sister who the Marine was dating, and their mom were all sleeper agents for the Shining Path, and weren't even related to each other.]]
** In "Brig Break", [[spoiler: Gunnery Sergeant Gentry]].
** In "Ares", Lieutenant Commander Gino Campisano is the senior weapons officer running the eponymous computerized weapons system onboard the destroyer: and suddenly, while off the North Korean coast, it starts to go crazy, operating without human input, and allowing no vessels other than ships to approach it. What no one knows is that Campisano is a North Korean mole, planted in the United States many years ago.
* ''Series/LasVegas'':
** Leo, one of the new guys at surveillance Ed hired in season 2, is revealed to be working together with a group of card counters.
** Adam, an employee remotely overseeing the card games in "Hit Me" is revealed to be sending electronic signals to a player.
* ''Series/{{Lost}}'': Seconds after Flight 815 crashed, Ben dispatched minions to infiltrate the survivors. They later turn out to be [[spoiler: Ethan]] in the main group and [[spoiler: Goodwin]] in the Tailies. In season two, [[spoiler: Michael]] is forced to act as a mole. In season three, an elaborate ruse is utilized to let Juliet infiltrate the survivors, but she [[HeelFaceTurn turns]] pretty quickly.
* ''Series/MacGyver1985'': In "The Enemy Within", Mac must discover the identity of a mole within the DXS who has caused the death of four agents.
* ''Series/{{Merlin}}'': Morgana was The Mole for most of season 3, and now [[spoiler:Agravaine has taken over the role, working for Morgana]]
* ''Series/TheMole'': This TV-program is the RealityShow version of this trope. The contestants engage in various challenges, and the better they do, the more money goes in the winning pot; at the end, the winner gets the pot, and the Mole gets the rest of the prize fund as a measure of how well they screwed things up. The contestants are also periodically quizzed about the Mole's identity and actions, with the poorest scorer eliminated. Played with: as a {{metagame}} strategy, non-Mole contestants also [[NiceJobBreakingItHero screw up]] on purpose, to fool others into thinking ''they're'' the Mole and thus do poorly on the quizzes. Sure, it decreases the winner's take, but it increases your chance of ''being'' the winner.
* ''Series/{{NCIS}}'': [[spoiler: Very Special Agent Lee]] is coerced into being a mole and learns, naturally, that [[spoiler:RedemptionEqualsDeath.]]
* ''Series/{{Neverwhere}}'': Used to good effect, where the BigBad's [[TheDragon Dragons]] inform the heroes that there is a traitor among them. The viewers are led to believe that it will turn out to be [[spoiler: the Marquis de Carabas, and it is made clear that the heroes believe this as well, but it's really the bodyguard, Hunter.]]
* ''Series/TheNewAvengers'': In "To Catch a Rat", a former agent recovers his memory after having amnesia for 17 years. He remembers he was hunting a mole known as 'the White Rat'. Realising the the Rat is still in the department, he resumes his hunt.
* ''Series/{{Nikita}}'': InvertedTrope where the character of Alex is set up to be the mole from the very start, and we see it all from her point of view. She remains the mole for the entirety of season 1. There is even a WasItAllALie moment coming from a more minor character, Thom, directed at the main character of Alex mid-way through the season.
* ''Series/{{Numb3rs}}'': In the season 3 finale, [[spoiler:FBI agent Colby Granger was revealed to be a spy for the Chinese.]] But in the premiere of season 4, [[spoiler:it was shown that he was a double agent the whole time.]]
** Played straight with Dwayne Carter. Though Colby's the only one who knows him well enough to be shocked. [[spoiler:He actually ''wasn't'', he knew exactly what Carter was up to, but he played it well enough that Don put it down to an error in judgment.]]
* ''Film/PerfectAssassins'': Leo turns out to be working for [[BigBad Greely]] to bring TheProtagonist to him.
* ''Series/{{Revolution}}'':
** [[spoiler:Nate Walker/Jason Neville]] is revealed to be a militia spy as soon as they get to Miles in the [[Recap/RevolutionS1E1Pilot pilot episode]]. In [[Recap/RevolutionS1E5SoulTrain episode 5]], it is revealed that [[spoiler: he is Tom Neville's son.]]
** In [[Recap/RevolutionS1E8TiesThatBind episode 8]], [[spoiler: Mia Clayton, Nora's sister, is not only this, but also a BountyHunter who captured Nora's fellow rebels and was working for that Sergeant Will Strausser]]. Nora was so disgusted that she abandoned her, even though they had made a promise to look out for each other.
** In [[Recap/RevolutionS1E9Kashmir episode 9]], [[spoiler:Joseph Wheatley, ostensibly of the rebels (possibly going by "Captain Burke"). In fact, he's been a militia spy for some time]].
** [[Recap/RevolutionS1E17TheLongestDay Episode 17]] had Miles quickly realizing that a mole has tipped off Monroe to the Resistance's whereabouts. [[Recap/RevolutionS1E18Clue Episode 18]] has Miles trying to find out the mole's identity, and [[spoiler: Jason Neville]] is the prime suspect. However, it turns out to actually have been [[spoiler: Jim Hudson]].
* ''Series/RobinHood'': A series 2 subplot in the 2006 BBC adaption features [[spoiler:Allan a Dale]] working as an informant for Guy of Gisborne, resulting in his exile from Robin's gang and the end of all his friendships when his treachery is unmasked. He ''is'' technically a good guy, so he also occasionally acts as a ReverseMole, though this is much more rare [[spoiler:until the season finale, in which he deliberately contradicts Guy's orders in a semi-suicidal bid to save the gang's lives and rejoins the band.]]
* ''Series/TheSarahJaneAdventures'': [[spoiler: Mr. Smith, though he turns to good for series 2.]]
* ''Series/StarTrekDeepSpaceNine'':
** Uses this with Michael Eddington. Originally a by-the-book secondary character who is more loyal to Starfleet than the rest of the cast, Eddington is eventually revealed to be a Mole for the rebellious Maquis.
** There's the time [[spoiler: Doctor Bashir was revealed to have been a Changeling impostor for the last several episodes.]]
** The Romulan [[StateSec Tal'Shiar]] is shockingly prone to moles at its highest ranks. [[spoiler:In "[[Recap/StarTrekDeepSpaceNineS03E21TheDieIsCast The Dies is Cast]]", Colonel Lovok reveals himself as a Changeling. And in "[[Recap/StarTrekDeepSpaceNineS07E16InterArmaEnimSilentLeges Inter Arma Enim Silent Leges]]", General Koval (the ''Chairman'' of the Tal'Shiar) is a double agent for the Federation.]]
* ''Series/StarTrekEnterprise'':
** Archer's steward Daniels turns out to be a time agent from the 31st century.
** DamselInDistress Rajiin is a portable X-Ray machine for the Xindi Reptilians.
** [[spoiler:Malcolm Reed works for an early incarnation of [[Series/StarTrekDeepSpaceNine Section 31]], while reporter Gannet turns out to be working for Starfleet Intelligence and Ensign Masaro for radical Earth group Terra Prime]]. [[spoiler:Reed]], at least, wasn't all too happy about [[spoiler:betraying his commanding officer, and when push came to shove, he stood by Archer]]. [[spoiler:He]] is one of the few characters of whom this can be said.
* ''Series/StarTrekVoyager'': [[spoiler:Seska was a Cardassian [[WeWillNotUseStageMakeUpInTheFuture deep-cover agent disguised as a Bajoran]] and]] Tuvok was a [[ReverseMole Federation agent]] (but [[FirstEpisodeSpoiler that's made known pretty early on]]), both infiltrating the Maquis on Chakotay's ship (much to his chagrin). When [[spoiler:Seska]] defects to the Kazon-Nistrim, a minor Maquis crewman (Michael Jonas) is her collaborator who remains on board ''Voyager'' (though the Kazon do their damnedest to play the middleman).
* ''Series/{{Supernatural}}'':
** [[spoiler:[[JerkWithAHeartOfJerk The angel Uriel]]]] turned out in their last episode to have been joined [[{{Satan}} Lucifer]]'s cause, trying to [[spoiler:recruit fellow angels to join him]] and killing those who refused. Note that the mole's successful conversions are never brought up again, making it possible that Lucifer loyalists may ''still'' be present in [[spoiler:the ranks of the Heavenly Host]] in show canon.
** The presentation of [[spoiler:angels as a whole, not just Uriel,]] may qualify, at least in [[spoiler:Season 4]]. They are initially portrayed as allies to the heroes whose differing view of what constitutes an "acceptable" sacrifice causes them to clash somewhat with the latter group. While they all turn out to still be reasonably sympathetic in their own ways, the season finale reveals that [[spoiler:the higher-ups in Heaven want Lucifer freed in order to kill him and create "Paradise," which is suggested by an actor for one of the characters to be a {{Dystopia}} of brainwashed human slaves, as opposed to Lucifer's vision of a [[KillAllHumans human-free]] universe]], and in subsequent seasons, even [[spoiler:angels not involved in this ploy]] are often enemies to be killed.
** ''Also'' revealed in their last episode, [[spoiler:[[TokenHeroicOrc the demon Ruby]]]] was ''another'' mole for Lucifer (not that they knew they were on the same side as the above mole or would have gotten along even if they had, due to FantasticRacism). More accurately, [[spoiler:Ruby was secretly working for demon queen Lilith, whom Ruby sent Sam after to kill on Lilith's own orders, as the other demon's death was the last seal needed to be broken to release their master, Lucifer, from his prison]]. While the character's true loyalties and agenda was ''long'' suspect by fans and by other characters, making this twist somewhat of an [[TheUntwist Untwist]], the way it played out was a satisfying resolution.
** Abaddon played this role 50 years before the series proper; she possessed and [[DevilInDisguise impersonated]] an inductee into an ancient mystical order in order to infiltrate and spy on them, planning to destroy them completely after learning all their secrets. [[TheBadGuysWin She succeeded on all counts.]]
* ''Series/TheVampireDiaries'': Damon starts out as a mole in the founder's council. But soon he becomes an actual member and turns out to be the most useful.
* ''Series/{{Whodunnit}}''" Is very similar to the mole in this respect, as one of the guests in secretly the killer
* ''Series/TheWildWildWest'': The episode "The Night of the Bleak Island". West's old friend Sir Nigel Scott turns out to be the BigBad.
* ''Series/TheWire'':
** During Season 2, the investigation into [[BigBad the Greek's]] syndicate is sabotaged at several points along the way by leaks from an FBI agent on his payroll.
** Agent Fitzhugh's apology to Daniels suggests that the leaking agent isn't corrupt, but another product of the FBI emphasizing counter terrorism over everything else. The Greek is protected from investigation by the FBI in exchange for counter terrorism intel.
* ''Series/TheXFiles'':
** Has this trope all over the place, PlayedWith and from various points of view.
** At the beginning, Mulder doesn't trust Scully. She's officially assigned to work with him, and everyone knows it's really to debunk his work. He thinks she might be connected with the conspirators, but she's honest and only submits her reports to their supervisors. Her loyalty soon belongs to Mulder completely, and he knows it.
** It pops up from time to time that Mulder and Scully's direct supervisor, AD Walter Skinner, might be dirty and collaborate with the shady conspirators. [[spoiler:Nope, he's allright and one of Mulder and Scully's strongest allies.]]
** From the conspirators' point of view, Mulder's {{Mysterious Informant}}s are The Moles who rat ''them'' out, trying to ruin their cause.
*** Deep Throat was involved with them and claimed that he wanted to atone for his deeds, therefore he helped Mulder in his quest for exposing the truth.
*** Mr. X was very pragmatic. He never made it a secret that he does what's best for him. He worked for the Cancer Man, and was informing Mulder behind his back.
*** [[spoiler:Marita Covarrubias]] played it on both side. [[spoiler:She]] was helping Muldler, and telling on him to the conspirators
** Scully's replacement for a brief amount of time in season 2, [[spoiler:Alex Krycek]]. He was an FBI agent assigned to work with Mulder when The X-Files division as shut down and Scully was sent back to teach at the FBI Academy. Mulder never fully trusted him, but it was a bit of a surprise when he was revealed to be telling on Mulder to the arc villain, the Cigarette-Smoking Man.
** In season 5, [[spoiler:Section Chief Blevins]]. He appeared in two episodes in season 1, and in one MythArc trilogy ({{WHAM Episode}}s par excellence), he was revealed as the dirty figure at the FBI who closely collaborated with TheOmniscientCouncilOfVagueness.
** In TheMovie (''Film/TheXFilesFightTheFuture''), [[spoiler:Well-Manicured Man is revealed to be one. The conspiracy group are in fact Well-intentioned Extremists, and he gives Mulder vital information, as well as a vaccine to save Scully.]]
** [[spoiler:Agenta Fowley and Spender, a pair of Agents put on the X-Files cases in season 6. Spender was more unassuming, never caring and happy to be destroying the files and informing the conspirators. But his partner Diana Fowley presented herself as Mulder's ex-girlfriend who still likes him and who are BirdsOfAFeather, like minds that should support each other and similar B.S. Mulder, to his credit, said that Scully's scientific approach had saved him and kept him honest. She collaborates with the Cancer Man and has Mulder subjected to horrific disease and treatment/experiment. However, she ultimately helps Scully to save him.]]