Code Lyoko (; stylized as CODE: LYOKO in season 1 and in all caps in seasons 2–4) is a French anime-influenced animated series created by Thomas Romain and Tania Palumbo and produced by MoonScoop for Cartoon Network, France 3 and Canal J, with the participation of Conseil Général de la Charente, Pôle Image Magelis, Région Poitou-Charentes, and Wallimage. The series centers around a group of teenagers who travel to the virtual world of Lyoko to battle against X.A.N.A., a hostile artificial intelligence which seeks to attack the real world. The scenes in the real world employ traditional animation with hand-painted backgrounds, while the scenes in Lyoko are presented in 3D CGI animation. The series began its first 97-episode run on September 3, 2003, on France's France 3, and ended on November 10, 2007, and on Cartoon Network in the United States on April 19, 2004, and ended in 2008 after its final seven episodes aired online at Cartoon Network video.
A follow-up non-canon series, Code Lyoko: Evolution, which used live action footage rather than hand-drawn animation to represent the real world, began airing in 2012. The series only consisted of one season of 26 episodes with the final episode airing in late 2013, leaving off on a cliffhanger with no second season or other sequel series planned due to MoonScoop's filing for bankruptcy shortly after in 2014.
In June 2026, it was announced that a sequel series was in development, which will be a direct continuation of the events of Season 4, with the entire original cast and writers returning.
Plot Jeremy Belpois, an 8th grade prodigy attending boarding school at Kadic Academy, discovers a quantum supercomputer in an abandoned factory near the school. Upon activating it, he discovers a virtual world called Lyoko, consisting of four separate environments known as "sectors" and inhabited by an artificially intelligent girl named Aelita. He also learns of X.A.N.A., a fully autonomous, malevolent, and highly intelligent multi-agent system that also dwells within the Supercomputer. Using structures on Lyoko known as Towers to gain access to the real world, X.A.N.A. can possess electronics, living beings, and other targets like a virus to wreak havoc. X.A.N.A. is determined to eliminate anyone aware of the Supercomputer's existence to achieve freedom to conquer Earth and destroy humanity.
In Season 1, Jeremy works to materialize Aelita into the real world and stop attacks caused by X.A.N.A. He is aided by his three friends, Odd Della Robbia, Ulrich Stern, and Yumi Ishiyama, collectively known as the Lyoko Warriors, whom he virtualizes into Lyoko through devices known as scanners. They achieve this by escorting Aelita to various Towers on Lyoko while under attack from hostile, X.A.N.A.-controlled programs known as monsters. Once a Tower is deactivated by Aelita, Jeremy can launch the "Return to the Past" program, which sends the world back in time and undoes damage caused by X.A.N.A., though anyone scanned into the Supercomputer retains their memory of the events. In the episode "Code: Earth," Aelita is finally materialized, but the group discovers that X.A.N.A. had planted a virus inside of her which will kill her if the Supercomputer is turned off. They realize that they cannot destroy X.A.N.A. without destroying Aelita in the process.
In Season 2, Aelita adjusts to life in the real world, under the name Aelita Stones, while Jeremy attempts to develop an antivirus program to free her from X.A.N.A.'s influence. On Lyoko, a fifth sector is discovered and the group explores more of Lyoko's secrets and mysteries. They begin to uncover information about a mysterious man named Franz Hopper, the supposed creator of the Supercomputer, Lyoko, and X.A.N.A. who went missing ten years ago. It is eventually discovered that Hopper is alive, but went into hiding in the uncharted parts of Lyoko to avoid X.A.N.A. Meanwhile, X.A.N.A. attempts to steal the Keys to Lyoko, lines of code which it can use to escape from the confines of the Supercomputer into the internet, from Aelita's memory. At the end of the season, the group discovers that Aelita is actually human and the biological daughter of Hopper, and, rather than being infected with a virus, is instead missing a fragment of herself. In "The Key," X.A.N.A. tricks them with an imposter, succeeding in stealing Aelita's memory and escaping the Supercomputer. Aelita appears to perish as a result, but is revived when Hopper restores her along with her missing fragment: the memories of her life on Earth before she was virtualized on Lyoko. We still never get any information on Aelita's mother, we don't ever really figure out whether or not she's even alive.
In Season 3, X.A.N.A., no longer bound to the Supercomputer, seeks to destroy Lyoko by erasing its four surface sectors until only Sector Five remains. Initially reluctant, the Lyoko Warriors decide to invite fellow Kadic student William Dunbar as the sixth member. Shortly after being virtualized, however, he is possessed by X.A.N.A. and proceeds to destroy the Core of Lyoko, destroying the virtual world and rendering the group unable to fight X.A.N.A., endangering the real world. After what they thought was their defeat, Jeremy receives a coded message from Hopper containing knowledge necessary for rebuilding Lyoko.
In Season 4, Jeremy and Aelita finish reconstructing Lyoko and construct a digital submarine known as the Skidbladnir to travel across the Digital Sea and destroy X.A.N.A.'s "Replikas," copies of Lyoko's sectors linked to X.A.N.A.-controlled supercomputers on Earth that were created for its goal of world domination. Throughout the season, X.A.N.A. uses William as a weapon to defend the Replikas and target the Lyoko Warriors. To prevent suspicion regarding William's disappearance, Jeremy manages to program a specter to take William's place at Kadic, although its seemingly unintelligent behavior confuses teachers and students alike. Near the end of the season, X.A.N.A. decides to draw energy from its Replikas to create the Kolossus, a gigantic monster which later destroys the Skidbladnir. Thanks to Jeremy's efforts, William is freed from X.A.N.A.'s control, but struggles to regain the group's trust. While Ulrich defeats the Kolossus, Hopper sacrifices himself to power Jeremy's "anti-X.A.N.A. program," which destroys X.A.N.A. forever upon activation. Shortly after, the group, albeit reluctant due to their nostalgia, decides to shut down the Supercomputer.
Characters Lyoko Warriors Jeremy Belpois Voiced by: Raphaëlle Bruneau (French); Sharon Mann (English) A prodigy student who finds and starts up the factory's Supercomputer while looking for parts to build a robot. In doing so, he reawakened Aelita, the virtual world of Lyoko, and the malevolent multi-agent system X.A.N.A. His goals are mainly driven by his desire to protect Aelita, whom he has a crush on, and save her from the Supercomputer and X.A.N.A. by materializing her on Earth. As part of the group, he specializes in programming new ways to defeat X.A.N.A. and monitors the group while they are on Lyoko. Because he is not very athletic and more computer savvy, Jeremy almost never goes to Lyoko, only going there twice and vowing to never go there afterwards. His workaholic attitude occasionally puts a strain on his relationships with the other four members of the group, who frequently refer to him as "Einstein". Once the Tower has been deactivated by Aelita, Jeremy will launch a "Return to the Past" to undo the damages caused by X.A.N.A.
Aelita Schaeffer Voiced by: Sophie Landresse (French); Sharon Mann (English) Mainly known by her alias Aelita Stones, she is the smartest of the group alongside Jeremy. At the beginning of the series, she was trapped within Lyoko inside the Supercomputer. She was originally thought to be an AI until it was revealed that she is the daughter of Franz Hopper, the creator of the world of Lyoko. When she was young, she lost her mother and a group of suited men implied to be government agents came to her home, causing her and Franz to flee and virtualize themselves on Lyoko. Between the virtualization and Jeremy's discovery of the Supercomputer, X.A.N.A. stole an important memory fragment that inhibited her from becoming fully human again. After this fragment is retrieved, she is no longer linked to the Supercomputer and becomes human again, but often has nightmares of her past life. She later enrolls as a boarder at Kadic under the alias Aelita Stones, claiming to be Odd's cousin. She reciprocates Jeremy's feelings for her, but he often strains their relationship by overlooking Aelita and her passions in favor of working on the Supercomputer. She is nicknamed "Princess" by her friends. Aelita is the only one capable of deactivating Towers on Lyoko to completely neutralize X.A.N.A.'s attacks. On Lyoko, she has an elf-like appearance similar to that of "Mr. Pück," a toy elf from her forgotten childhood. She has the ability to create or remove objects, such as rocks or bridges, from the virtual environment, which is called "creativity" by Jeremie. She had no weapons or offensive abilities until season 3, when she developed the ability to create "energy fields," pink balls of plasma that can be thrown or used to block enemy fire from a distance. In the fourth season, Jeremy programmed light pink-white angel wings as part of her new virtual attire, allowing her to fly and carry one person; the star-shaped bracelet she wears allows her to activate them by waving her hand over it.
Odd Della Robbia Voiced by: Raphaëlle Bruneau (French); Christophe Caballero and Matthew Géczy (English) The comic relief of the group. Odd has great academic potential, but rarely uses it; as a result, he gets bad grades due to his lack of studying. Despite his rebellious and impulsive persona, he is shown to be nice. He shares a dorm with Ulrich and has a dog named Kiwi, whom he hides in a dresser because pets are not allowed at Kadic Academy. He is considered a ladies' man and has dated many girls at his school, though these romances are short-lived. Prior to attending Kadic, he lived with his parents and his five older sisters. Odd's blond hair has a purple spot in the middle and, since he was virtualized on Lyoko for the first time, worn up in a spike. He is implied to be of Italian descent, and speaks the language fluently. On Lyoko, he is dressed like a cat, with a tail and clawed gloves that shoot "laser arrows." In the first season, he had a precognitive ability he called "Future Flash", but it was deleted before the second season and replaced by the defensive ability to create a purple force-field by crossing his arms in front of his body. Other abilities include the ability to use his claws to climb on walls like a cat and control monsters upon contact.
Ulrich Stern Voiced by: Marie-Line Landerwijn (French); Barbara Weber-Scaff (English) A more reserved member of the group, Ulrich struggles to share his feelings and learn in order to live up to his parents' expectations, as they pressure him to achieve well in school. In his off-time, he practices Pencak silat with Yumi, whom he has a crush on. He suffers from vertigo, which makes it hard to participate in activities such as rock climbing. Due to his many activities, Ulrich has a rather muscular build, leading many girls, particularly Sissi, to consider him handsome. On Lyoko, he wears a yellow and brown outfit inspired by Japanese samurai. His main weapon is a katana, which he can dual wield. His "Supersprint" ability allows him to dash at high speed, and his "Triplicate" power lets him create two clones of himself. He can combine these abilities in a technique called "Triangulate," using his clones to form a triangle around an enemy and ambush it from behind as it is distracted.
Yumi Ishiyama Voiced by: Géraldine Frippiat (French); Mirabelle Kirkland (English)