History YMMV / CodeLyoko

** Many fans don't consider the live action sequel ''Series/CodeLyokoEvolution'' part of the series.

** Jérémie. He's either seen as an {{Adorkable}}, well-meaning guy with the social skills of a baked potato or a selfish DesignatedHero who pressures his friends to do as he says and is obsessed over his goal to the point of being unlikeable.

** Patrick Belpois's one-shot appearance in Season 4 was enough to cause tons of fanfiction featuring him as a regular character, often even upgrading him to a full-fledged Lyoko Warrior. There was a time during the show's peak in which you would actually struggle to find a [[AlternateUniverseFic reimagining]]/[[{{Continuation}} Season 5]] fanfic in which he would ''not'' be included.

** One common fanfic people tend to write about surrounds potential recruits to join the Lyoko Warriors. Jim, Sissi and Patrick (Jérémie's cousin) being the three standout candidates, Jim (who was briefly a member of the group in the two-part finale of Season 1) and Sissi (who was one of group's founders before being kicked out).
** Another is people showing off Jérémie's Lyoko form since viewers know it exists, but they never actually got to see it.

* {{Fanon}}: The name "Team Lyoko" was ''never'' used in canon in the actual show; the fans came up with it. Same was true for the name "Lyoko Warriors" initially, but it became AscendedFanon.

* LostInMediasRes: This was easily the show's biggest flaw of season 1 next to the {{Filler}}. Very little is established in the first few episodes of season 1. While it did add to the mystique of the show, it made just as many viewers confused and think there was no real MythArc due to the constant use of the ResetButton.

** [[https://www.youtube.com/watch?v=-B_1KXLoIBE&feature=emb_title Jim saying "I'd rather not talk about it"]] anytime he mentions an old career of his.

** The Tarantulas needing to kneel in order to fire their lasers could be seen as a design error by XANA, but it does make them look surprisingly professional when they fire.

* RealismInducedHorror: While XANA is often mocked for its overcomplicated and silly attacks, it can also do more simple attacks which hit really close to home.
** In "Revelation", it simply sends a text message to Odd, pretending to be a secret admirer to lure him into the woods, and traps him into a well with a hose spraying water down to drown him. This is a simple yet effective strategy adopted by kidnappers and predators who want to lure naive children and teens in an isolated place to further their goals.

** Season 4, while generally considered a step up from Season 3 and a good season overall, gets flak for being too long, not capitalizing on the huge potential of the season 3 finale, having too many boring {{Filler}} episodes with weak plot direction [[note]]The season starts off somewhat focused as the first eight episodes are dedicated to the main and subplots overall, but then falls into the filler afterwards, with massive gaps in-between Replika episodes[[/note]], and generally not reaching the heights Season 2 did in events, with massive {{Flanderization}} taking place, particularly on Jérémie and Odd. It also didn't fix the tone dissonance from Season 3; though the stakes were technically higher, the comedic elements remained as a poor sore thumb against the plot itself.

** News of the new project, ''Series/CodeLyokoEvolution'', being live-action and with little involvement of the original creators, were met with fervent hatred in some places. Even fans who were willing to give the show a chance were harsh about its quality, as it was a ToughActToFollow and generally seen as inferior to the original series.
** The novels have also been criticized for the liberties they take with the source material; the details of how the group found Lyoko, the fight against XANA, and the Hermitage's location are all markedly different. Because of these changes, for instance, William never joined the Lyoko Warriors and plays an almost non-existent role in the story, and the cast are a year younger. [[ArsonMurderAndJaywalking Also, Aelita and Anthea's hair is red instead of pink]].

** The series had the tendency to introduce {{One Shot Character}}s who had a lot of potential only for them to either vanish or become background fodder after their first episode, particularly in Season 1. Some noteworthy examples include Theo (Ulrich's first look at having a [[TheRival rival]] long before being given a permanent one in William), Taelia (a {{Doppelganger}} of Aelita, which could have made for some interesting interactions between two characters that looked like one another) and Patrick (Jérémie's more socially successful cousin, whom he had an one-sided estranged relationship with).

** The plot point of Jerémie going to Lyoko and having his own Lyoko Warrior avatar, something the fans have been wondering about since the very first season of the show, was swiftly killed offscreen with the other characters ''deriding'' it. Even whenever he did go to Lyoko, either it was not shown or his avatar was his own human form. All in all, one can almost see the producers flipping the bird to the fans about this. The novels at least do show it off, revealing that his form is akin to Peter Pan, but is still a JokeCharacter not capable of fighting, so the concept, while at least more solid, is still never developed more.

** Perhaps the largest case of this would be Project Carthage, an enigmatic military project that Franz Hopper desired to destroy, due to its ability to affect world-wide communication networks. Basically put, this project is the ''very reason the show's plot exists at all'', and yet very little attention was ever given to it after Season 2, when any chances for it to be mentioned throughout the story are dropped for the most part. Not even the sequel series, ''Series/CodeLyokoEvolution'' directly mentions it; only the novels have ever dealt with the subject.

** The characters' ''enormous'' foreheads are subject to many, many jokes.

** Similarly, her slow walk into the Tower to deactivate it when XANA's attack on Earth [[JustInTime is on the verge of succeeding]], courtesy of early show's frequent use of StockFootage, still leads to frequent jokes in the fandom about yelling at Aelita to hurry up. This is even after later episodes began using new footage that shows her ''running'' into the Tower and showing an overall greater sense of urgency.

** Aelita's slow walk into an activated tower in the early seasons has been subjected to a ton of funny jokes throughout the series run, with many in the fandom yelling at her to hurry up. To the point it even got fanart.

** People blaming various inconveniences on XANA, usually technical difficulties.

** "'Pick on Yumi' time", thanks to Yumi being a frequent target of XANA. (See FanNickname)

* TheProblemWithLicensedGames: The games based off this series either range from decent at best to a lesson in masochism at worse. The first game on the DS verges on FakeDifficulty thanks to nearly ''all'' the monsters operating under InstantDeathRadius; The following DS game ''Fall of X.A.N.A.'' was decent, albeit slow and uneventful in gameplay; The console game ''Quest for Infinity'' was alright as well, albeit extremely biased towards ranged characters over melee characters since melee characters deal pitiful damage by comparison.

** [[BrainwashedAndCrazy Aélita Schaeffer's xanafied self]] combines her good self's intelligence with XANA's ruthlessness. [[Recap/CodeLyokoS2E6 Pretending to be her good self in her first appearance]], she manipulates Jérémie Belpois into sending her to Lyoko, talking Yumi Ishiyama into going with them when Jérémie expresses reluctance in Aélita going on Lyoko alone. On Lyoko, XANA-Aélita stays ahead of her fellow [[Characters/CodeLyokoLyokoWarriors Lyoko Warriors]] through clever uses of her Creativity powers, leading to her all but completing her mission. Returning as a recurring villain, XANA-Aélita works well in tandem with XANA and its monsters, successfully destroying three of the four main sectors and setting up XANA's victory in that season. [[Recap/CodeLyokoS4E25 In her final appearance]], XANA-Aélita cleverly reacts to Ulrich Stern's attack, stealing one of his swords and defeating him with only a limited use of her powers, nearly completing her mission. Always thinking on the fly and [[SuperpoweredEvilSide showing how truly dangerous Aélita's powers could be]], her xanafied self proved to be one of the Lyoko Warriors' most dangerous threats.

** One episode has Patrick Belpois shout out Geronimo while attacking XANA-Sissi, he would be unaware that it would eventually be the signature catchphrase of [[Franchise/DoctorWho a Time Traveling Time Lord who wears bow ties]].
** One episode has Ulrich mention that the music XANA made was rather unoriginal. Fast forward to TheNewTwenties when AI that was able to "Create" content like music, art, and prose was basically "Taught" it by feeding prompts.

** Theo Gautier, a one-shot character who displayed interest toward Sissi then toward Yumi, is either used to get Sissi out of the way while averting this trope, or portrayed as a {{Jerkass}} and abusive boyfriend toward Yumi so she can run into Ulrich's arms (despite the fact he is even less of a threat than Sissi is).

** Taelia is also suprisingly popular for her short appearance, mainly for bearing a strong ''spooky'' resemblance to Aelita (except for having red hair) and her name being an rearrangement of Aelita's.

** Brynja Herinsdotir, the titular girl of the episode "Kadic Bombshell" is this for very obvious reasons, mainly for being a MsFanservice having by far the ''biggest'' breasts of the girls to the point of putting ''Sissi'' to shame. Many had hoped she'd return, but ultimately got PutOnABus due to Sissi's jealousy in order to maintain the StatusQuoIsGod.

** One common fanfic people tend to write about surrounds potential recruits to join Team Lyoko. Jim and Sissi being the two standout candidates.

* {{Moe}}: ''All'' of the Lyoko warriors are considered BadassAdorable by fans.