History Main / OnlyOnePlausibleSuspect

* This trope is used frequently in various versions of ''Franchise/ScoobyDoo''. Subverted in one episode of ''WesternAnimation/WhatsNewScoobyDoo'', though: the crook in "It's All Greek to Scooby" turns out to be [[AnticlimacticUnmasking some random person the gang has never met beforehand]]. Velma naturally is rather displeased and keeps insisting her theory about who was the monster was at least plausible.

* In the 1982 all-comedy issue ''ComicBook/TheFantasticFour Roast'', the team is being feted at a celebrity roast with everyone in the Marvel universe in attendance. But a mysterious figure is out to sabotage the proceedings and after numerous attempts, Ben "The Thing" Grimm says that the only other person besides Reed smart enough to ruin the party is ComicBook/DoctorDoom. However, Doom approaches the dias and [[NotMeThisTime pronounces his innocence.]]

* Towards the tail end of ''Series/TorchwoodMiracleDay'' we're told there's another evil {{Mole}} in the CIA other than the ObviouslyEvil, FatBastard that was outed earlier. There are three CIA operatives that aren't part of the main cast. One is DaChief and working pretty diligently with Torchwood and wants the case solved and the mole outed. The other is developing the software to find the mole. That leaves the last one, who was [[spoiler:featured prominently in the first episode, who we had just been reminded exists the episode prior, and who just had her wardrobe change up to [[EvilIsSexy low cut cleavage showing dresses]]]]. To be fair though, the audience is let in on it before the heroes, who were busy juggling the IdiotBall the entire season.

* ''Manga/{{Beastars}}'': For the anime. In the manga, when it's time for Legosi to investigate Tem's killer, we see a large batch of potential suspects that Legosi plans to interview, and we see that the drama club has a large amount of behind-the-scenes members. It never really gets around to exploring them, but a reader could at least be thrown off by thinking it'll get to them eventually. In the anime however, there are no extra members, leaving the only potential suspects to be Bill and Riz. Once Bill was shown to be rather physically weak, this left Riz as the only potential remaining option.

* ''WesternAnimation/BatmanUnderTheRedHood'' opens with the Joker killing Jason Todd and then introduces the Red Hood in the next scene (which takes place years later). Batman spends the middle portion of the film trying to figure out who the Red Hood is, but literally all of the film's major characters other than the Red Hood are shown fighting and/or talking to the Red Hood, so even a viewer who's not familiar with the comics will probably figure out that [[spoiler: the Red Hood is a resurrected Jason Todd]] before Batman does.

* Literature/HarryPotter: "RAB" is [[spoiler: Regulus Black, Sirius' dead brother]]. He's a fairly obscure character who'd only been mentioned in passing a couple of times prior to the reveal, so it probably ''would'' have been hard to figure out... Were it not for the fact that there are no other characters in the series with those initials. SpoiledByTheFormat was also an issue, as foreign versions of the books that changed the character's name had to change the initials accordingly.

* ''Franchise/FireEmblem'': The Tellius games have a real problem with this.

* In the early Android Saga of ''Manga/DragonBall'', Bulma turns out to be the mother of KidFromTheFuture Trunks. There are a number of clues to this (they have the same hair color in the manga, he shares her FamilyThemeNaming, he wears the logo of her father's company on his jacket), but the thing that turns it into this trope is that when Trunks was introduced, between Chi-Chi getting married and Launch [[ChuckCunninghamSyndrome vanishing forever]], she was the ''only'' named unmarried female character who'd appeared in the manga in about three years. In fact, this [[DerailingLoveInterests caused some issues]] since this meant Bulma was the only preexisting character who could romance Vegeta, resulting in a rather abrupt timeskip hookup.

* TheMole in ''VideoGame/Persona5'' is very easy to guess simply from the fact that they have a [[RelationshipValues Confidant]] that automatically ranks up during the story, and because they're the one party member who never got much attention in pre-release marketing. [[spoiler:This may have been to disguise the ''real'' twists: the Phantom Thieves knew he was a mole from the start, and the whole thing was a setup by a third party.]]

* ''Anime/AttackOnTitan'': The female Titan is [[spoiler: Annie Leonhart]]. Armin figures out that she's another human-shifting Titan almost as soon as she appears, but her true identity is a mystery for most of the first season. What makes it obvious is that we know from Eren Yeager's transformation that the Titan form shares certain features with their normal human form (such as hair color). The female Titan is blonde, and there are only two blonde women of note on the show -Krista and [[spoiler: Annie]]. Krista was shown to be elsewhere during the female Titan's attack, so that just leaves [[spoiler: Annie]].

[[folder: Comic Books]]

* In ''Film/CaptainAmericaTheWinterSoldier'', Steve Rogers sets out to discover who has ordered the attacks on both him and Nick Fury. Only one plausible suspect is shown, [[spoiler:Alexander Pierce]], especially after he makes several vaguely ominous statements like "[[UtopiaJustifiesTheMeans to build a better world sometimes mean tearing the old one down]]". Perhaps in awareness of this, the film makes little attempt to disguise [[spoiler:Pierce]] as the culprit and it only takes five minutes after he and Steve meet for him to become a visible antagonist. The only reason that savvy viewers might be surprised is because [[spoiler: Creator/RobertRedford]] is [[PlayingAgainstType not known for]] playing bad guys.

* ''Film/TheRiseOfSkywalker'' introduces a spy within the First Order who leaked vital information to the Resistance, enabling them to launch a counter strategy in time to clinch victory against [[spoiler:Palpatine]]. There's not enough time between the movies for any known allies of the Resistance to infiltrate the First Order as a mole (''TROS'' is set only a few months after ''Film/TheLastJedi''), and the only First Order members of any significance are [[spoiler:Kylo Ren and General Hux]]. Since [[spoiler:Kylo]] is apparently working for [[spoiler:Palpatine]], it leaves [[spoiler:General Hux]] as the only possible candidate for the mole, [[spoiler:especially since his animosity with Kylo does give him a motive to want to see his reign end]]. Suffice to say, he does end up revealing himself to be the spy.

* Literature/HarryPotter: "RAB" is [[spoiler: Regulus Black, Sirius' dead brother]]. He's a fairly obscure character who'd only been mentioned in passing a couple of times prior to the reveal, so it probably ''would'' have been hard to figure out... Were it not for the fact that there are no other characters in the series with those initials. SpoiledByTheFormat was also an issue, as foreign versions of the books that changed the character's name had to change the initials accordingly.
* In Creator/WilkieCollins's "My Lady's Money," [[spoiler:Felix Sweetsir]]--he is the only person with a motive to steal the money.
* In "The Pliable Animal" by Creator/HarryHarrison, a prince is murdered on a planet with the strictest possible ThouShaltNotKill policy... [[spoiler:for everyone but the king, whose duties include performing the occasional MercyKill on trapped dangerous predators]].

* Season 3 of ''Series/TheFlash2014'' introduces a new masked villain, "Dr." Alchemy. It also introduces one new supporting character: [[spoiler:Julian Albert, an unsympathetic crime-scene investigator who seems to be obsessed with metahumans]]. Guess who Dr. Alchemy turns out to be. However, in a twist, [[spoiler:[[TheKillerInMe he doesn't even realize he is Dr. Alchemy]], and is GoodAllAlong]].

* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' episode "Rarity Investigates", Rainbow Dash gets framed for a petty act of treachery so that she won't break the long distance speed record. There's only one non-recurring character in this episode: Wind Rider, the holder of said record.
* ''WesternAnimation/BatmanUnderTheRedHood'' opens with the Joker killing Jason Todd and then introduces the Red Hood in the next scene (which takes place years later). Batman spends the middle portion of the film trying to figure out who the Red Hood is, but literally all of the film's major characters other than the Red Hood are shown fighting and/or talking to the Red Hood, so even a viewer who's not familiar with the comics will probably figure out that [[spoiler: the Red Hood is a resurrected Jason Todd]] before Batman does.

* TheMole in ''VideoGame/Persona5'' is very easy to guess simply from the fact that they have a [[RelationshipValues Confidant]] that automatically ranks up during the story, and because they're the one party member who never got much attention in pre-release marketing.

** Bertram is [[spoiler:Renning]]. His helmet doesn't cover his mouth, and there's not a lot of other characters with [[YouGottaHaveBlueHair green goatees]].

* In the early Android Saga of ''Manga/DragonBall'', Bulma turns out to be the mother of KidFromTheFuture Trunks. There are a number of clues to this (they have the same hair color in the manga, he shares her FamilyThemeNaming, he wears the logo of her father's company on his jacket), but the thing that turns it into this trope is that when Trunks was introduced, between Chi-Chi getting married and Launch [[ChuckCunninghamSyndrome vanishing forever]], she was the ''only'' named unmarried female character who'd appeared in the manga in about three years.