* ''[[RosarioToVampire Rosario+Vampire's]]'' MonsterOfTheWeek formula progressively stopped being the ''main'' formula due to these three:
** Kuyo and his student police force, [[spoiler: who beat up the UnwantedHarem and actually ''killed'' Tsukune; this was the first time he was injected with blood, and also caused the first instance where Inner Moka was in any real danger.]].
** Ruby's master helped the transition along, in an arc that [[spoiler:focused heavily on FantasticRacism, which has since become one of the series' most prevalent themes. She was planning to wage war on humanity, and was willing to cut down her own adopted daughter to do so]].
** Midou and the outcast monsters, [[spoiler: who beat up ''Inner Moka,'' killed Tsukune ''again,'' and caused this next blood injection to put the Evil in SuperpoweredEvilSide.]] After this incident, the main theme of FantasticRacism between humans and monsters, and between monsters and other monsters, really began to take over.
** Second season manga started out mostly silly and comedic, even the first serious villain, the doppleganger, had his own share of silliness. Then, in volume 3, we meet Miyabi, whose first act is to sexually harass Mizore, as well as steal her first kiss. This is NOT PlayedForLaughs, as the molestation destroys her emotionally, ultimately making her [[spoiler:''commit suicide''. Fortunately, she was saved by Kurumu]]
* ''{{Trigun}}'':
** Legato Bluesummer's introduction changes the tone in a single frame. It's a bright and sunny day, the kids are playing with Vash. Then out of nowhere, Legato. He killed and ate the friendly shopkeeper Vash was just speaking to, and feels it would be a downright shame if the little girl Vash just bought an ice cream for would have to be next. The entire scene is completely horrific, but what cements it as this is the opening shot of the usually lighthearted and goofy Vash looking legitimately terrified for the first time in the series that clearly indicates exactly how bad things are about to get.
** Monev follows Legato's cue and begins shortly afterwards - while previously Vash was always able to stop the villains before they can do serious harm, the guy basically moves down everyone in his path (including women and children) to get his target - and he actually enjoys this collateral damage. This is also the first time that Vash really loses it, and comes close to killing Monev.
* ''Manga/RurouniKenshin'' has actually two of these:
** The first one is Udo Jin-e. The series had started rather lightly... and in came this [[EvilIsHammy loud]] BloodKnight with a permanent SlasherSmile, an until-then-unseen degree of cruelty, the capacity of either killing you bloodily or put you in an [[spoiler: AndIMustScream]] position, and the dubious "honor" of showing us some glimpses of what would happen if [[spoiler: Kenshin ever fully reverted to his Battousai side.]]
** The second is Saitou Hajime. His introduction signaled the arrival of the Kyoto Arc (and the much more dangerous villain Shishio) whereas previously, the series had been a light-hearted action comedy where, a few serious villains like the aforementioned Jin'e and Aoshi aside, Kenshin's everyday life continued as a light-hearted and comical romp.
* [[spoiler: Kurata]] from ''Anime/DigimonSavers''. Before he had appeared the only real "dark" parts of the anime resulted from Gotsumon's incredibly hostile attitude toward Ikuto/Keenan. When [[spoiler: Kurata]] arrived, he brought genocide (including the deaths of both of Ikuto/Keenan's "parents", resulting in genuine TearJerker scenes) and singlehandedly made the season the darkest one yet. For once we had a genuinely evil [[spoiler:''human'']], and also BY FAR the most evil character ever to grace the franchise.
** Devimon in the original ''Anime/DigimonAdventure''. While the first few episodes of the show were simple MonsterOfTheWeek, his appearance in Episode 8 introduced a proper, intertwined story arc and highlighted that the show wasn't kidding around anymore. It got somewhat lighter - though with even more MythArc - in the short 'Etemon arc' - only for Myotismon to firmly seal the series in CerebusSyndrome.
** While ''Anime/DigimonTamers'' was always more serious and thinky than the other series, Beelzemon's arrival causes a big shift. DarkerAndEdgier went from meaning "Digimon don't automatically [[DeathIsASlapOnTheWrist respawn at the Primary Village]] anymore so fights actually ''[[AllDeathsFinal count]]''" to [[spoiler: Impmon makes a DealWithTheDevil, kills Leomon, and Jeri gets VERY close to the DespairEventHorizon. From there we go straight to an arc that gets ''Anime/NeonGenesisEvangelion''-level freaky and TheHeartless uses Jeri's grief to power up its beasts by [[MindRape mind raping]] her for weeks on end]]. Things got bleak at that point. They ''still'' forgave Beelzemon. Eventually.
** Lucemon's reveal as the ManBehindTheMan of Cherubimon in ''Anime/DigimonFrontier'' leads to a dark turn where the plot becomes trying to prevent TheEndOfTheWorldAsWeKnowIt before he's released, with [[FailureIsTheOnlyOption Failure As The Only Option]].
* ''Manga/SoulEater'' started off as a zany wacky serious with a very eccentric cast. Then [[MadScientist Medusa]] showed up with her abused and unstable child Chrona, and released [[EldritchAbomination Asura]] which caused a the series to take a darker shift where people started dying and going insane and the zany imagery became more nightmarish. Asura himself qualifies, any time he appears the series comic relief stops, with Medusa still having had some humorous scenes.
* Zophise from ''GashBell''. Gash Bell tends to get a lot of these, because most of the enemies tend to be fairly goofy, it's jarring when you get someone who's playing for keeps.
* Raditz from ''Dragon Ball Z'', who jumped the series out of being comedy-focused altogether.
** Frieza. While he is not completely serious and still has comedic lines, he has the honor of being one of the most evil villains in the entire franchise.
** Before either of them, there was Piccolo Daimou. Before him, the {{Big Bad}}s in ''DragonBall'' were mostly comedic, and the only exceptions still weren't especially dangerous, and were {{Non Action Big Bad}}s. He however, was a {{Badass}} HeroKiller, and he effectively succeeds in his goals of obtaining the Dragon Balls and [[TakeOverTheWorld taking over the world]], it's just that Goku manages to kill after he does both.
** General Rildo in ''DragonBallGT''; until he showed up, ''GT'' was a throwback to the comedy of early DB.
** UrExample in ''DragonBall'' is Tao. He was the first serious villain in the franchise with no humorous qualities to him and caused the first on-screen deaths in the franchise, which back he appeared was actually quite shocking due to how lighthearted the manga was.
* ''MazingerZ'' has a weird example in Count Brocken. To put it simply, he is the first villain to harm(and actually killed) innocent people. And from that, he proceed to do some horrible stuff. He is so notable amongst the villains that in fact, right in this wiki, he is the most notable person that is mentioned when the Dark part of Mazinger Z is talked about, complete with creepy design than the already creepy Ashura and the show indeed goes into the darker parts after this. The weird part ? at the same chapter he appeared, he provided the single [[CrowningMomentOfFunny most hilarious moments]] in the entire series in a rather stupid way. Its kinda hard to think hes the same person who killed person on the screen for the first time.
* ''Manga/MahouSenseiNegima'':
** Fate Averruncus from the manga. His first appearance saw him petrifying a bunch of people and essentially defeating the party (who had been putting up a good fight up to that point) all on his own. When he appeared a second time he averted BloodlessCarnage by [[spoiler: [[ImpaledWithExtremePrejudice impaling Negi with a hunk of stone]] and scattering everyone across the world]]. This was the trigger that eventually led Negi to begin using BlackMagic. Oh, and Fate's ultimate goal is [[spoiler: to erase the magic world from existence, [[OmnicidalManiac along with everyone in it]].]]
** Evangeline serves as an earlier example. Once it's revealed that not only is she a vampire with a PowerLimiter curse that also binds her to the school, but the one who cursed her was Negi's father, and she needs Negi's blood to break it, the series started its GenreShift from harem comedy to shonen.
* Fate Testarossa of ''MagicalGirlLyricalNanoha'' is another Fate that served as this, shifting the focus away from the standard GottaCatchThemAll, MonsterOfTheWeek, MagicalGirl format upon arrival and eventually sending the plot careening towards [[TheFederation a more interdimensional scale]].
** [[EvilMatriarch Precia Testarossa]]. ''Nanoha'' really went dark when [[KickTheDog she was introduced]]. How exactly ''was'' she introduced? [[spoiler:Beating (the clone of) [[DarkMagicalGirl her daughter]], with a whip for not gathering ''every'' MacGuffin.]] After she left, it became slightly lighter again for the later two seasons.
** At least until Jail, in the third season, mentioned that he had all of the Numbers (functionally, and sometimes biologically, ''[[ParentalIncest his daughters]]'') impregnated with clones of himself.
** The Huckebein from ''FORCE'' are taking the series to a new level of dark.
* Mukuro Rokudo from ''Manga/KatekyoHitmanReborn'' is an example of this trope; in the beginning of his story arc, a number of major characters are badly beaten. His appearance also signals a major GenreShift in the series, which had been comedic until this point.
* ''Manga/FullmetalAlchemist'':
** Although it started with a horrifically failed attempt at resurrecting their mother, the series begins kind of hopeful with Edward and Alphonse Elric traveling to find the Philosopher's Stone to set things right. Then they encounter the Sewing Life Alchemist Shou Tucker whose [[spoiler:experiments that transformed his wife and daughter into pained chimeras]] gives a sign of the darker events that will follow.
** The introduction of the homunculi lead the series into darker territory after [[spoiler: Envy murders Hughes.]]
* Makubex in ''GetBackers.'' Before the IL recovery mission, Ban and Ginji were retrieving things like expensive melons and a blind girl's violin. Makubex threatened them with an atomic bomb.
** Then came the true arms of Venus and all that, but Makubex was the first to give them a real battle.
** The expensive-melon mission ''was'' where they met [[BloodKnight Kuroudo Akabane]] "[[NamesToRunAwayFromReallyFast Dr. Jackal]]", who would show up in most later arcs and both act as this trope and subvert it. His being Ginji's StalkerWithACrush would serve as comic relief, even as the fact he's interested in the arc's conflict shows it's nothing to sneeze at (remember, his response to "[[NoOneCouldSurviveThat Even you can't survive a nuke]]" is "[[WorldOfCardboardSpeech We don't know that, I've never tried]]").
* Takasugi Shinsuke in ''Manga/{{Gintama}}'' is the first seriously evil character, and is featured in the series' first serious arc, benizakura. He is probably also the only main character in the show who doesn't have comedic side.
* Though Tsutomu Nihei's ''{{Blame}}!'' was never what you'd call light-hearted, the appearance of The Safeguard marked a dramatic shift in the storyline to something much more epic.
* [[EmbarrassingFirstName Pantyhose Tarou]] was only the first of a succession of very serious, very powerful foes in ''RanmaOneHalf'': while earlier opponents were always ineffectual antagonists versed in wacky, fun, harmless MartialArtsAndCrafts tournaments, Ryugenzawa's {{Orochi}}, [[KiAttacks Prince Herb of the Musk Dynasty]], [[TheDrifter Ryuu Kumon]], and ThePhoenix King Saffron followed in Pantyhose Taro's footsteps by forcing Ranma & Co. into more serious, no-nonsense combat, where death was suddenly a very real possibility.
* ''[[Anime/MobileSuitGundamZZ Gundam ZZ]]'' started out almost ridiculously lighthearted but after a bunch of {{Ineffectual Sympathetic Villain}}s, Haman Karn gets into the plot and all of a sudden the heroes really need to worry. Another Gundam example is ''GGundam'' though only the first few episodes are rather easy going until Devil Gundam and Kyouji are first mentioned.
* ''Anime/PrincessTutu'' starts off as a fairly light, straight-up GottaCatchEmAll MagicalGirl series for the first few episodes. Then [[DarkMagicalGirl Princess Kraehe]] steps in and '''''BAM!''''' -- here comes the GenreShift.
* Depending on if we're talking about the manga or the anime of ''RozenMaiden'', either Barasuishou or Kirakishou counts. It should be noted in Kirakishou's case that when [[spoiler:the most [[CheerfulChild cheerful and childlike character]] in the whole franchise [[ImAHumanitarian gets eaten]] by her]], you know there won't be much more comedy. Barasuishou on the other hand [[spoiler:both directly and indirectly causes the deaths of all the other characters deliberately just to please her father, Enju, a jealous apprentice to Rozen]], and with her dead serious attitude that everybody must participate in the Alice Game, it is not very surprising.
* Butch and Cassidy of ''Anime/{{Pokemon}}'' be headed for this at their first appearance, being a TerribleTrio in their own right with a [[TheMole crooked Officer Jenny]]. It didn't last long, but at least other members of Team Rocket manage to stay properly intimidating -- especially when they show up in force. Even Max admits that the cast is pretty lucky that they usually only have to deal with the TerribleTrio that stalks them around.
** Pokémon Hunter J surpasses them in malevolence, being the darkest villain to ever appear in the series and to never suffer from VillainDecay, not to mention being one of the few characters that was actually [[spoiler: killed off]]. While technically not a villain, Paul seems headed this way, being more abusive towards his Pokémon than anyone else.
** Another example is Sabrina, who popped up earlier than Butch and Cassidy and before J did. Sabrina only appeared for two episodes, and after her arc everything returned for normal, but for years later, no villain surpassed Sabrina in terms of scariness[[note]]Even though Sabrina was closer to a WoobieDestroyerOfWorlds, as it is implied that she was incapable of controlling her psychic powers before Haunter came along[[/note]]. Let's face it: she transformed trainers she defeated into dolls, and was just plain creepy. J may be more evil and has no qualms committing murder, but at least she doesn't turn people into dolls. (Only she's a gym leader and not a villain)
** Combining this with NotSoHarmlessVillain is the Team Rocket trio themselves in the ''Best Wishes'' series.
** Cyrus of Team Galactic intended to destroy the entire world and everyone with it (even the other members of Team Galactic) while possessing Azelf, Mesprit, Uxie, Dialga, and Palkia to create a new dimension for him to rule. [[spoiler: And he apparently dies in the episode right after J.]]
** [[spoiler: Dr. Yung]] in The Mastermind of Mirage Pokemon tortures Pikachu, and was previously expelled for his twisted experiments. [[spoiler: And after his defeat he runs into his burning lab and is presumably incinerated.]]
** [[spoiler: N, Ghetsis, Colress, and Team Plasma in ''Best Wishes 2 Episode N''.]]
** Some of the villains form the movie series are these, including [[Anime/PokemonTheFirstMovie Mewtwo]], [[Anime/{{Pokemon3}} Molly Hale]], [[Anime/Pokemon4Ever The Iron-Masked Marauder]], [[Anime/PokemonArceusAndTheJewelOfLife Marcus]] and [[Anime/PokemonZoroarkMasterOfIllusions Grings Kodai]].
* ''PokemonSpecial'' was all fine and dandy until Giovanni popped up. Similarly ''PokemonDiamondAndPearlAdventure'' had mook's and the mildly threatening Admins such as Saturn or Mars, but it got dialed up when Cyrus came around.
* Yami Marik in ''Anime/YuGiOh''. Contrary to the original Marik he was ''not'' content to hide in the shadows relying on minions and trickery, he would personally duel and make his opponents writhe in pain in the Shadow Games he inflicts on them. In both the original Japanese and the English dub, Marik was focused on Yami Yugi and only saw his friends as pawns to be used to get to him. Yami Marik on the other hand didn't care who he faced, he would make them suffer and eventually MindRape them when they lost. He also underwent an EvilCostumeSwitch, trading in Marik's BareYourMidriff pink shirt for a sleeveless black one with a BadassCape, the Eye of Ra was permanently displayed on his forehead, his hair was suddenly spiking into the air, and his voice is deeper with [[VoiceOfTheLegion an echo effect]].
** Yubel in ''Anime/YuGiOhGX''. After [[AmbiguousGender their]] appearance, IdiotHero Juudai starts his downward spiral, [[DeathIsCheap characters start dying]] and some of the standard humor in the series begins to disappear as the it takes its turn towards full DeconstructorFleet territory. Even in 4Kids GagDub which made the season LighterAndSofter compared the Japanese version, Yubel has no comedic quirks.
** The Three Tenors in ''Anime/YuGiOh5Ds''. While the full extent of their plan isn't revealed for some time, when they first began to appear they rolled out the Meklord archetype and sent Yusei into a HeroicBSOD when suddenly the iconic Synchro monsters of the series that almost all the duelists rely on became useless, forcing them to re-evaluate their strategies in addition to the mystery of the new villains that had rolled into town.
** Vector in ''Anime/YuGiOhZEXAL''. His first appearance marks the start of the Barians taking matter into their own hands. When he shows up again later, he reveals he's been pretending to be Yuma's friend for an entire arc, causing a HeroicBSOD and a brief rift between Yuma and Astral. After his defeat, his response is to wake up the evil god of the Barian World, solely so he can keep screwing with Yuma and Astral.
* [[Anime/NeonGenesisEvangelion Evangelion]] was a [[{{Deconstruction}} dark series]] to begin with, but the events of the "Action Arc" (from Asuka's arrival up to Leliel/Twelfth Angel) were relatively light-hearted, with Misato and Kaji seemingly making amends, and Shinji starting to gain some confidence. ...Then came Bardiel/The Thirteenth Angel, and everything went to Hell, culminating in [[TheEndOfTheWorldAsWeKnowIt End of Evangelion]].
** From a different perspective, you might think that ''Evangelion'' inverts this trope; the series first becomes truly dark not with the arrival of a new character, but the sudden disappearance of an old one - Toji, who was selected to pilot the ill-fated Unit-03.
** ''RebuildOfEvangelion 2.0'' is, for most of its running time, a much LighterAndSofter story than the episodes it's adapting. There's a good amount of comedy, we see the kids bonding, Asuka's less of a {{Jerkass}}, and the angel battles ("[[FanNickname Clockiel]]" and Sahaquiel) are focused more on [[Awesome/RebuildOfEvangelion awesomeness]]. Then Bardiel shows up and possesses Unit-03 [[spoiler:with Asuka inside]], and the movie goes straight into terrifying territory.
* In ''Manga/TheWorldGodOnlyKnows'', when Fiore shows up, she starts off as a cute IneffectualSympatheticVillain working behind the scenes. [[spoiler: Then she crosses the MoralEventHorizon by trying to [[BoomHeadshot snipe Kanon/Apollo]], and succeeding in stabbing them.]]
* ''MedakaBox'' once was a lighthearted, comedic series about school adventures of a GodModeSue and her harem. After 14 chapters of that, the first serious antagonist, [[KnightTemplar Unzen Myouri]] appeared, heralding oncoming GenreShift into a fighting series with a brutal bloodbath (no one supposedly died, but a ton of people probably were put in hospital for years). And just as the arc, started by Unzen's appearance was about to end, Kumagawa Misogi stepped on the scene, signaling a lesser shift to even more DarkerAndEdgier tone.
* ''ChirinNoSuzu'' was all cute and adorable until the Wolf appeared and the mood became very dark.
* ''Anime/PuellaMagiMadokaMagica'' looked like it was going to be another typical magical girl show, albeit one with unusually dark undertones. Then came Episode 3, which introduced Charlotte, the third Witch. The moment when she [[spoiler:ate fan favorite and CoolBigSis Mami alive]] was the moment when the series showed just how dark of a {{Deconstruction}} of the genre that it could be. And this was only a taste of [[FromBadToWorse what would come later]].
** Unusually for this trope, [[spoiler: Charlotte is defeated shortly after she killed Mami.]]
** Hell, one of the ''protagonists'' qualifies. The first episode introduces four out of the five main girls, three of which are shown to be genuinely nice and kind-hearted people, and the fourth of which is somewhat mysterious and jaded. All other humans are similarly nice, normal people. Then one episode after Charlotte, we're introduced to a fifth magical girl, a psychopathic JerkAss who threatens to hunt down and ''kill Sayaka''. That's Kyoko Sakura for you, folks. There's a ''reason'' why she didn't appear back when the show was pretending to be a typical MagicalGirl show. [[spoiler: She [[CharacterDevelopment gets better]] and gets a FreudianExcuse, too.]]
** Happens again with a heroic character in ''Anime/PuellaMagiMadokaMagicaTheMovieRebellion''. As soon as Homura [[spoiler: discovers that she and her friends are in a witch barrier]] and takes off her glasses and hair ribbons, the movie's tone shifts from a faux-TastesLikeDiabetes parody to a sinister mystery. And [[spoiler: she makes the movie even darker ''again'', near the end, when she performs a FaceHeelTurn, becomes a self-proclaimed demon, and then takes over the universe after her friends rescue her, instead of just ascending to magical girl heaven]].
** The SpinOff manga ''Manga/PuellaMagiKazumiMagica'' has [[spoiler: Yuuri]]. Another unusual example because she only took the role in the fourth chapter, having appeared as a MysteriousWatcher in the first two and an easily defeated antagonist in the third. But in the fourth, [[WhamEpisode hoo boy...]]
* ''{{Claymore}}'' never made any pretenses to be anything other than a dark series, but whenever [[spoiler: Priscilla]] turns up, things are going to go south very, VERY fast.
* Mag Mel from ''{{Bakugan}}''. Previous villains were dark, but Mag Mel is by far the most terrifying villain yet with an extremely dark storyline. He was [[SealedEvilInACan imprisoned for genocide]] and that's before the series ''even started!'' Once he appeared, he {{Mind Rape}}d Dan and Drago in a very horrific manner. Once he was finally free, he started trying to burn Gundelia to the ground. In scope of sheer evil and darkness, he's the darkest and most horrifying villain in the entire series!
* ''Manga/{{Bleach}}'' has a few examples.
** The first is Sosuke Aizen, particularly after TheReveal. While the build up ''to'' TheReveal was far from light hearted, it still had a few bouts of comedy when he was off screen, By the time of the Arrancar arc, there's very little comic relief compared to the last two, and when there is, it's usually interrupted by the antagonists. And the man has no sense of humor himself. His reaction to SEEING comic relief unfold is to wonder whether or not it's a bad strategy to take him off of his guard. Even before outing himself as a villain, Aizen was completely humorless. During an extended flashback, Shinji comments on how uptight he is.
** Shukuro Tsukishima was this during the Xcution arc, though he did have a sense of humor. It just happened to be [[AxCrazy incredibly vicious]].
** In the "Thousand Year Blood War arc", the Wandenreich have easily taken the cake. [[spoiler: The devastation they have brought to the Soul Society within the span of only a few minutes was unprecedented in the story to that point and the leader is willing to sacrifice his own followers for even slight infractions.]]
* The entire first episode of ''LightNovel/CubeXCursedXCurious'' seemed to be setting up for a lighthearted SliceOfLife comedy series. Episode 2, enter: Peavey.
* ''VisualNovel/HigurashiNoNakuKoroNi'' seems like a light-hearted harem comedy until [[spoiler:Miyo]] pops up and starts putting things in Keiichi's head.
** Ooishi can tend to be this for specific arcs as well. When he shows up, you know MoodWhiplash is about to kick in. It even becomes a plot point in Tatarigoroshi-hen, in which Keiichi sees him as the personification of the end of their happy days.
* ''TigerAndBunny'' has several, each one putting the series deeper into much darker territory:
** Lunatic - VigilanteMan, first to kill somebody in the series. Whenever he shows up, things starts turning grim. [[spoiler: He has a DayInTheLimelight in episode 16, probably the most depressing episode in the entire series]].
** Jake Martinez - while Lunatic was treated seriously, he was at least a WellIntentionedExtremist, while Jake [[spoiler: held the entire city hostage, and sent the main character and four of his friends to the hospital]] ForTheEvulz. He was the first villain who was shown to take pleasure in evildoing.
** [[spoiler: Doctor Rotwang and Cis]] from episode 15, who have been indirectly responsible for starting a chain of [[TearJerker heartbreaking moments]] that prevailed through the rest of the series.
** And finally the BigBad [[spoiler: Albert Maverick mindraping Barnaby in a scene strongly reminding of date-rape scenario, being the first to murder non-villainous cast member and framing Kotetsu for it]].
* [[EldritchAbomination Space]] [[StarfishAliens Monsters]] from ''{{Gunbuster}}'' - for the first two episodes series is lighthearted and funny, being basically [[SportsStories sport story]] with [[RealRobot mechas]] and serious elements were nothing more but backstory. Once the first battle has come, it turned into desperate fight for survival and stayed that way even after the shift to the SuperRobotGenre.
** ''{{Diebuster}}'' starts as sympathetic and optimistic [[SuperRobotGenre Super Robot]] MonsterOfTheWeek show, but after one of [[spoiler: true Space Monsters, the same ones as in Gunbuster]] shows up, things go to hell very fast.
* ''Anime/PhiBrainPuzzleOfGod'' played with this - new villain, Herbert Müller, didn't started the shift to more serious tone. In fact his appearance stopped one that was already taking place, by putting delay on plans of previously established villain [[spoiler: Rook]], who resumed them after Müller was out of picture and became Knight Of Cerebus himself.
* It's interesting to watch the increase of the power of the villains in ''Manga/OnePiece''. Alvida and Morgan possessed no real threat to Luffy, and Buggy wasn't really much of a challenge either. Afterwards, Captain Kuro and Don Krieg were much more menacing, but still relatively weak: They were just bad guys who happened to show up at the time. Everything changed when Arlong came along, and while the series retained its light-hearted tone for the most part, seeing what the stakes are when a real monster gets involved changed the world of the series forever. Follow this up with an enemy Luffy can't fight in the form of Smoker, and it's clear that the end of the East Blue saga was when the series hit its stride.
** And then Crocodile, Nico Robin and the Alabasta arc up the ante, going from relatively minor conflicts to an all-out civil war. It also marks the point where the heroes start ending up on the verge of defeat (''repeatedly'') by an opponent far beyond their level, as well as expanding on the series' MythArc (becoming far more than Luffy searching for some buried treasure and becoming King of the Pirates.)
** Admiral Akainu finally averts the "Nobody dies outside of flashbacks" rule [[spoiler: by killing Ace.]] Blackbeard follows it up soon after by [[spoiler: killing Whitebeard and bringing about a new age of pirates.]]
** ''Manga/OnePiece'' usually has a strange SortingAlgorithmOfEvil with its BigBad bosses, ranging from dangerously competent to incompetent with each antagonist, with the occasional appearance of a serious threat like a Warlord like Kuma or Mihawk and the Three Admirals show up in which the situation drastically becomes more threatening. Then Akainu, the last of those three Admirals makes his debut and completely breaks the StatusQuo by [[spoiler: killing Ace]], and the story's gotten significantly more DarkerAndEdgier in both in story and its enemies, while still retaining its positive elements.
* ''Transformers: WesternAnimation/BeastWars II'' is an incredibly light-hearted show with hilarious characters, that hardly ever takes itself seriously. And its villains are no exceptions - Galvatron - the BigBad is a narcoleptic who spends most of the show asleep, leaving his inept kid brother Megastorm to run the show with effeminate TheDragon (Starscream), a thug who can only repeat his own name (BB), and Beavis and Butt-Head (Thrust and Dirge) under his command. Cue the last 10 episodes of the show, where Galvatron wakes up, takes command, and we learn that he has a gigantic DoomsdayDevice en route to Gaia, which he intends to use to destroy the whole planet and siphon the Anglomois energy. And then things go grimdark... Gigastorm (Megastorm after his makeover) is fatally wounded and dies in Galvatron's arms, and the whole series ends with [[spoiler: all the Maximals sacrificing themselves to destroy the Nemesis, in the end flying up to 'robot heaven'. Granted, Beast Wars Neo retcons this.]]
* In ''Manga/{{Naruto}}'', although the first major villain, Zabuza, had already been introduced we saw the kids handling on their own against him with the help from their teacher, Kakashi; when Orochimaru is introduced, he is shown to be a villain that even the most experienced jounin fear and ends up killing the Third Hokage. Much later, the reveal of Pain serves as this since shortly after his introduction he [[spoiler:kills Naruto's sensei, Jiraiya]].
** Tobi also qualifies. While he seemed like a klutz at first, it's later revealed that it was all an act to disguise his true nature as the mastermind of the Akatsuki. And when he drops the act, things get more serious.
* Much like its SpiritualSuccessor ''Claymore'', ''{{Berserk}}'' is nothing short of a DarkFantasy series. However, the TV series is considerably LighterAndSofter than its manga counterpart, so for the majority of the [[PragmaticAdaptation TV series']] run, it was basically composed of Guts and Griffith talking about dreams and ambition, the Hawks battling the Tudor Empire for the Kingdom of Midland and a bunch of political stuff, and developing characterization that wasn't derailed by {{Adaptation Induced Plothole}}s or AdaptationExplanationExtrication. But when Nosferatu Zodd was introduced with his prophecy halfway through the series, followed by the introduction of the [[BigBadDuumvirate Godhand]] toward the end [[spoiler: especially the transformation of Griffith]], we knew that this series was going to [[DownerEnding end on a bad note.]]
** Within the manga itself, the Skull Knight, despite not being a villain, manages to be this since whenever he shows it, tends to mean things will get bad.
* Over the course of the first half of ''MonColleKnights'', the heroes had no problem repeatedly beating back the LaughablyEvil VillainsOutShopping Count Collection, Bacchi, and Guuko. Then [[AntiVillain Dark Angel Zaha]] shows up and turns some of the heroes' monster friends against them by brainwashing them. And if that's not enough, there's [[BigBad Reda]], a DangerouslyGenreSavvy Dark Angel who is so powerful that even Shiru has problems with him, and he [[spoiler:actually plans to use the Monmon Items to summon Oroboros so he can have it [[OmnicidalManiac warp all life into a formless existence, with him as the omnipotent center of time and space]]]]. OhCrap...
* Manga/TsubasaReservoirChronicle has a rather interesting example where this trope is actually a ''heroic'' character, (or at least a good guy). Confused? [[spoiler: Halfway through the manga, it's revealed that the main character Syaoran is actually a clone of another "Syaoran" that The BigBad had locked away. The Original "Syaoran" eventually manages to escape and gets warped to where the heroes are, but by that time, Clone Syaoran (known as "Cloney" by the fans) has reverted to a heartless automaton. Cloney becomes an antagonist while "Syaoran" becomes the new main character]], and from then on, the manga is a hell of a lot darker than it was before.
* The Metarex in ''SonicX'' fit this trope really well. So basically, the first two seasons of the show were pretty much light-hearted and funny in tone. Then cue the arrival of the Metarex, a group of dangerous cyborgs and robots that plan to harness the power of the Planet Eggs to [[spoiler:cause a plantation of the entire galaxy and wipe out all flesh and blood so plants can rule]]. The Metarex come in many different types of their own, like the one-shot villain Red Pine, the LaughablyEvil [[TheBrute brute]] Yellow Zelkova, emotionless monsters like Pale Bay Leaf as well as Black Narcissus, who [[MoralEventHorizon captured and tortured Chris and Cosmo and used them as bait to lure Sonic to him]], and [[TragicVillain the tragically villainous]] MagnificentBastard Dark Oak himself.
* ''Manga/FairyTail'' has two. Jellal is the first villain who poses a serious threat to the cast's lives, and is trying to return [[UltimateEvil Zeref]] himself, as opposed to the various demon's Zeref created that have been sought out in earlier arcs, or power skirmishes that have otherwise been the focus. In addition, while previous tragic backstories have been about losing or fighting with family members, his and Erza's past is full of all kinds of slavery, torture, and betrayal. After Jellal, every arc is some serious threat that will either kill the cast or destroy the country. The second is Hades, who is also the second villain to seek Zeref. He turns the first lighthearted arc in over 100 chapters into a fight for survival that ends with the series no longer being a NobodyCanDie story, many characters' sufferings turn out to have been for no reason, Zeref potentially unleashed on the world, and he [[spoiler:inadvertently summons an evil dragon that leaves the core cast LegallyDead for seven years]]. Zeref himself, oddly enough, has yet to invoke this trope.
** [[spoiler: He does after the time skip, where he plans to ''wipe out humanity''.]]
* In the ''Anime/MonsterRancher'' anime, General Durahan's arrival signaled the end of lighthearted episodes; he even appears right after a lighthearted one. He's also a literal knight. Even though he isn't around for very long, he still allows [[BigBad Mu]] to get the magic stone, which allows him to overcome his WeakenByLight AchillesHeel, the only thing keeping him from killing the protagonist.
* {{Toriko}} was a light hearted food hunting series with the occasional creepy GT Robots, and the arc after them is another finding secret recipe mission much like prior to their appearances. [[GutPunch then Tommyrod shows up]]. Unlike Starjun and Grinpatch, who were NobleDemon and AffablyEvil villains respectively, Tommyrod kept [[BodyHorror all kinds of hideous parasitic insects within his body]], who seriously tries to kill Toriko [[spoiler: and actually manages to win the fight, despite getting an awesome asskicking]], and from there the story gets much darker.
** Starjun is a milder example, with a no-nonsense personality, having a dark aura, and being the truly first time that [[spoiler: Toriko comes close to death]].
* ''Anime/TengenToppaGurrenLagann'' has Thymilph, who [[spoiler: [[HeroKiller manages to kill Kamina]]]], though he ended up ''tame'' compared to Lordgenome and [[spoiler: the Anti-Spirals]].
* ''Anime/CodeGeass'' is by no means a light show, but it still has its breather moments. Except, for one, whenever V.V. meddles, invariably causing things to [[FromBadToWorse get worse]].
* By the time [[spoiler:Deep Blue finally steps out of the shadows]] in TokyoMewMew, things start taking a turn for the darker and more dramatic for the Mew Mews.
* Vicious from ''Anime/CowboyBebop''. Not only is he the main antagonist of the five episodes he's in, he's also a major threat to Spike.
* ''KirbyRightBackAtYa'' features some Demon Beasts/monsters that take the otherwise lighthearted and comedic anime on a turn for the darker and more dramatic. First up, we have Powered Masher / Masher 2.0 in a DarkerAndEdgier episode of the same name (in English, of course). Sure, Masher was already powerful enough in his original appearance in the second Knuckle Joe episode before that, but Masher 2.0 is even more dangerous and powerful than he was before. He did a good amount of damage to Knuckle Joe and even now comes equipped with a powerful laser. After Joe defeats Masher 2.0, everything goes back to being comical and happy, until...
** ...we get introduced to Mumbies in Episode 84. This dude is considered to be even more dangerous than most of the bad guys Kirby's already faced before. Throwing in a creature that Kirby almost can't fight due to its trickery and supply of surprises was enough to give Kirby himself a hard time. And this thing's not the only one; there's even more Mumbies scattered across the universe, hidden on each planet all with the same goal of causing chaos and killing Star Warriors. After Kirby defeated this particular Mumbies, everything went back to happiness and humor. But not for long...
** Twelve episodes later came the even DarkerAndEdgier five-part series finale, which featured the ''truly competent'' Destrayers. These things were the main reason why Pupu Village / Cappy Town was getting burned to a crisp and suffering from a SugarApocalypse. In fact, a blast fired from one of the Destrayers even knocked off a piece of... you guessed it... ''Kirby's WARP STAR!'' Yikes!
* ''Manga/CityHunter'' is a strange version. It started serious (albeith with some dose of silliness), then got comedic in the Sayaka Ryujin arc and stayed comedic for most of its run, only for Sonia Field [[spoiler: who wants to kill Ryo because he ''killed her father'', who also was his partner at the time]] to bring back the seriousness. There had been other serious story arcs (chiefly Rosemary Moon's), and it happens that [[spoiler: Sonia's father forced Ryo to kill him to protect her]], but this time the story remained serious as it was before Sayaka Ryujin, culminating in the major antagonist of the initial part of the manga returning to settle the score.
* ''TenchiMuyoGXP'' has [[SpacePirate Tarant Shunk]], a man so ruthless that even other pirates fear him. The episode that introduces him is the first and only one in the entire series to show any violent bloodshed.
* While the original ''QueensBlade'' series (both the anime and the original gamebook continuity) didn't have any of them (except [[spoiler:Aldra in the Rurou no Senshi manga]]), in the ''QB Rebellion sequel'' we have ''three'' of them for continuity: [[spoiler:Captain Liliana and Ymir in the anime, as Liliana stole Vingt from Huit, and later Ymir uses dark powers for controlling the undead, and Sigui in the gamebook continuity, as she's the one of the few people that gives Annelotte, the main heroine from ''Rebellion'', a real challenge]].
* ''Manga/KamisamaKiss'' is mostly a RomanticComedy but when Akura-Ou shows up things get darker and people start dying violent, bloody deaths and in large numbers.
* "BoboboboBobobo" is a WidgetSeries filled with {{Shonen}} and SurrealHumor, then Czar Baldy-Bald the III, and this misanthropic megalomaniac causes the series to get much more violent, especially by Shinsetsu where he achieves his BigBad status again to make the empire worse than it was before.
* While the series maintains an episodic MonsterOfTheWeek format even after her appearance, the addition of [[spoiler:Northa]] to the cast of FreshPrettyCure marked the arrival of a far stronger villain who was also dead serious about her intentions. [[spoiler:Even the monsters of the week got stronger (thanks to her new sorewatase seeds).]]
** After [[spoiler:Northa]] came the Dark Precure of ''Anime/HeartcatchPrettyCure'', a villain who makes her mark by defeating the veteran Cure Moonlight in her first appearance. Every other appearance pushes Cures Blossom, Marine and SixthRanger Sunshine into corners until Moonlight gets back into the saddle.
** ''Anime/HappinessChargePrettyCure's'' Phantom, the "Pretty Cure Hunter" is this. Unlike [[spoiler:Northa]] or the Dark Precure, Phantom actually ''defeats'' Pretty Cure, depowering them, trapping them in crystal mirrors and shoving them in what appears to be a ''graveyard''.
* The ''Manga/SailorMoon'' manga's first arc Queen Beryl as this role, when she started to actually act, it meant Usagi' love interest was [[BrainwashedAndCrazy brainwashed]] and [[EldritchAbomination Queen Metalia is revived]].
** The ''[[Anime/SailorMoon anime]]'' biggest case was Sailor Galaxia. Both arcs, when she's starting acting mark an end to the series comedic moments, and lots of characters dying.
* Sensui from ''Manga/YuYuHakusho'' who killed the main character of the damn series and succeeded in opening the tunnel to demon world, which potentially could have wiped out human life. He's also a manipulative corrupter, ruthlessly sacrificing children as pawns and introduced really dark nihilistic themes into the series.
* ''Manga/AnimalLand'' starts off with Tarouza, a human child, dealing with relatively simple challenges from trying to get the various animals to get along in harmony, to defending against gigantic carnivores. Then comes Jyu, another human child who is a SocialDarwinist, who sees all that Tarouza is trying to do be an upfront against nature and thus burns down all of the hard work Tarouza did in seven years.
** Jyu is then upstaged in more ways than one by Giller. He is a mysterious MadScientist type character who causes all sorts of harm towards the animals in the world. Also he uses {{Animalistic Abomination}}s known as Chimeras.
* ''Manga/{{Hellsing}}'' made it clear from the start that it was not going to be a lighthearted series with the number of people seen getting mutilated and its AntiHero protagonist, but the initial threats simply consisted of vampires who actions were limited to committing random murders. Then the series revealed the rise of vampires was the doing of group of AxCrazy Nazi vampires called Millennium, who from their leader's [[RousingSpeech RousingSpeechOfEvil]] make it clear they have much greater ambitions, which we see start with butchering the entirety of London.
* Things in ''LightNovel/DateALive'' quickly got serious when [[{{Yandere}} Kurumi]] [[AxCrazy Tokisaki]] entered the picture. So much that there was a BreatherEpisode before her arc.
* In ''Anime/KillLaKill'':
** Things quickly got darker and darker from the moment [[CuteAndPsycho Nui Harime]] showed up in episode 11, especially since that she's the one [[spoiler: who killed the heroine's father]].
** After [[spoiler: Satsuki's betrayal and attempted decapitation failed]], Ragyo Kiryuin showed just what a living nightmare she was. For all her campiness, her villainy is played brutally straight, shown when she [[spoiler: thrashes Satsuki and imprisons her, and then brainwashes Ryuko and sews Junketsu ''into her skin'' before sending her to kill Nudist Beach, and then putting into action a plan to ''blow up Earth'']].
* ''TenchiMuyo'' is typically a lighthearted harem comedy, in both the original OVA and in ''TenchiUniverse''. The exceptions in both occur when Kagato shows up. While more powerful villains than him appeared in the OVA, they never had as much of an impact as him.
** The movie ''Tenchi In Love'' is mostly like the rest of the lighthearted "Universe" series with barely a mentioned of the heavily built up EldritchAbomination Kain brought up at the start of the movie. But then towards the end of the film, Kain shows up, and unlike villains in the franchise before him, he actually kills somebody, in an outright horrific manner to boot.
** ''TenchiinTokyo''. When [[BigBad Yugi]] shows up, the show's wacky humor drops dramatically and dark twists starts appearing in the show's plot.
* While ''Anime/PantyAndStockingWithGarterbelt'' never loses it's humor, the plot takes a turn for the darker once CoDragons [[EvilCounterpart Scanty and Kneesocks]] debut. Though they quickly fall into VillainDecay, some of their plans can be pretty damn [[FridgeHorror scary when you think about it]]. Then there's their [[BigBad master]], [[spoiler:Corset]], who is far more competent than his minions, [[BadBoss who he frequently tourtures]] [[YouHaveFailedMe for their failures]] (by the way, they're [[AbusiveParents his daughters]]). His plan? Create HellOnEarth.
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