[[quoteright:256:http://static.tvtropes.org/pmwiki/pub/images/24_t_965.jpg]]
[[caption-width-right:256:[[VillainousBreakdown NOT]] [[LogicBomb LOGICAL!]] '''[[VoiceOfTheLegion NOT LOGICAL!]]''']]

[[folder:Code Lyoko]]

* An Alternate Universe example: What if what happened to the Real Life factory in France happened in the show before Jeremie turned on the Supercomputer? That would mean that Aelita and Franz would have ''died!''
* Some of XANA's attacks do border on this, especially if it's a widespread offensive. XANA-possessed characters can be particularly creepy, and many examples of XANA trying to murder the protagonists (like ''electrocuting Jérémie'') can induce nightmares.
** Most ways that XANA tries to kill Jérémie can cause Nightmare Fuel. Jérémie gets electrocuted by one of the power sources for the ''Supercomputer'', as well as getting electrocuted by the specters.
** Also, when he discovers that the one [[spoiler:Franz Hopper]] is actually a polymorphic specter in disguise, it gets pissed at him, turns into smoke to invade his airways, and proceeds to suffocate him while Ulrich can do nothing but watch.
* A lot of the psychotic expressions XANA-fied William makes.
** Not just him actually, ''any'' xanafied person will often arbore a quite scary expression with VoiceOfTheLegion to complete.
* [[http://i56.tinypic.com/25zqc5i.jpg This lovely shot]] of a XANA-possessed Aelita.
** Want to make this concept even scarier? Watch "Ghost Channel" (where Aelita proves she's able to essentially do the same things XANA could do in the first season, and without needing the towers, could do so unopposed if she wanted to) and then imagine what she and XANA could accomplish if he was able to control her more often.
* Jérémie scores one with the "Marabounta". Basically, sort of purple goop starts covering Lyoko, devouring initially every XANA monster, then going after the Lyoko Warriors. The heroes were definitively {{squick}}ed -- especially when it ''ate Yumi''. (Seriously, just watch the scene where she is EatenAlive by the thing. Imagine how ''she'' must have felt. You have to wonder just why these kids even do this.)
* [[EverythingsDeaderWithZombies "Attack of the Zombies"]]. The title pretty much says everything by itself.
** It really doesn't. XANA possesses Kiwi, Odd's pet dog, and uses him to spread a zombifying virus through the school. Most of the group is trapped in the cafeteria, and William is trying to keep them there (give him some credit, he doesn't know about Lyoko yet). Odd is bitten and Ulrich and William have to restrain him. Imagine seeing your best friend gagged and tied up and trying to bite you while moaning in the VoiceOfTheLegion.
** Jeremie gets bitten before Aelita deactivates the tower and has a horrifying transformation. He can barely gasp out 'Return to the Past now!' and his voice is already ''changing''... if Aelita had been seconds late...
* Of course, in animation there's a ''lot'' of ArtEvolution between pilot episodes and the resulting series themselves, but ''Garage Kids'' (in certain scenes) combines OffModel and UncannyValley and turns them UpToEleven. To clarify: Ulrich's avatar has eyes that seem like they came from the first ''VideoGame/CrashBandicoot1996''. But still, TropesAreNotBad (see WhatCouldHaveBeen in the [[Trivia/CodeLyoko Trivia tab]]).
* "Killer Music" borders on the High Octane variety. Imagine an [=MP3=] becoming a successful hit. Now imagine it being [[SingleStanzaSong a simple, looped sentence]] (I've seen the Italian version and it was like, "Uh, hah, you will never win") creepily reminiscent of synthethizeritis. ''[[OhCrap Now picture it putting each of its listeners in a comatose state.]]'' It's especially terrifying when Odd falls victim to it, as he's stuck with a huge grin on his face, thus looking like he'd been murdered by SelfDemonstrating/TheJoker.
* Who else [[BowelBreakingBricks shat bricks]] when we saw [[spoiler:XANA's disguise of Jérémie breaking down]] from "Ghost Channel"? XANA Jérémie's "[[LogicBomb NOT LOGICAL! NOT LOGICAL!]]" after the kids decide that he's the fake Jérémie because he doesn't understand that Jérémie ''would'' virtualize himself to save his friends. And then the scene where he screams and then tries to kill the characters.
-->'''XANA:''' [[EvilLaugh HAHAHAHAHAHAHAHAHAH]]! [[VoiceOfTheLegion YOU ARE GOING TO DIE]]!!!
** Let's admit it, Ghost Channel was the '''scariest''' episode of [[WesternAnimation/CodeLyoko Code Lyoko's]] first season. For a season with episodes that were mostly {{Filler}} and that involved XANA attacking and the team having to deactivate a tower in [[{{Cyberspace}} Lyoko]] (and that were pretty creepy on their own), it really drove home '''what''' kind of a threat this nutcase of a computerized OmnicidalManiac was, to the point where his [[BringMyBrownPants pants-browningly]] horrifying OneWingedAngel form at the climax now serves as the page image. [[WhamEpisode Good Lord]].
* There are also the attacks where XANA [[AttackOfTheKillerWhatever takes over animals and uses them to attack Kadic]]. So far, we got wasps, rats, birds, boar, ''wolves''... the latter even had a scene with Ulrich falling in the middle of said wolves, who immediately start to attack him. The Return to the Past barely saves him.
* The time XANA took control of a dangerous criminal.
** In the episode with the above criminal, just how casually Jeremie informs Ulrich (via cell phone) that after he replaces the Supercomputer's nuclear core, XANA [[spoiler: is going to kill him.]] [[TroublingUnchildlikeBehavior No 12-year-old should be that calm in that situation.]]
* Just how quickly Odd and Yumi deteriorate in "Ultimatum" due to being LockedInAFreezer. Yumi starts shivering first and by the time XANA has gotten tired of waiting for Aelita to give herself up, is reduced to being barely able to stand and weakly crying Odd's name as XANA prepares to kill him.
** And then there's the added idea that Odd might have accidentally caused XANA's later attack of creating an ''obscenely'' cold blizzard by telling XANA that cold is lethal to humans.
* The Zero Gravity episode. Think about it; the evil computer virus has taken control of FREAKIN GRAVITY to the point where it can just LAUNCH PEOPLE INTO ORBIT WITH EASE.
* The amount of times Ulrich has nearly died in general. No child would be perfectly fine with that, not even mentioning how many of them were different e.g. burned alive/dehydrated to a dangerous degree, crushed, frozen, mauled to death etc.
** The others don't escape either considering Yumi and Odd both nearly froze (Yumi ''twice''), Yumi shared the SaunaOfDeath event and Jeremie, Yumi and Odd all nearly drowned at least once each.
** Every member of the group has been electrocuted at least once. ''Everyone.'' And it's not PlayedForLaughs, ever.
* In the second-to-last episode, the group decides not to send William to Lyoko since he just got freed from XANA's influence. XANA decides to make them regret that decision, and immediately possesses William's body again, prompting Yumi to devirtualize herself and fend him off to protect Jeremie. What follows is the most [[NoHoldsBarredBeatdown brutal]] [[CurbStompBattle beatdown]] ever seen in the real world.
[[/folder]]

[[folder:Novel series]]
* [[spoiler:XANA as Eva]] has determined the fastest way to get a necessary item is to [[spoiler:maim whoever has it]]. At one point, before getting on the airplane to France, she is seen with luggage, new clothing, and a computer, with no indication as to where she got any of it, except that the T-shirt is ''stained''.
[[/folder]]

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