Monsters are programs created by X.A.N.A., to fight the Lyoko Warriors in Lyoko, protect X.A.N.A's activated towers, and to be used as X.A.N.A. sees fit. They are directly materialized into Lyoko. According to codelyoko.fr, X.A.N.A. uses a base template which is used to make it easier to create new monsters.
It is possible that they are created from a basic program, with all their characteristics, allowing X.A.N.A. to create many monsters, all almost identical. This would correspond to the program created by Jeremie to virtualize vehicles. In some episodes, such as Marabounta, X.A.N.A. virtualizes creatures directly in the field as Jeremie does with the Lyoko Warriors. it is shown that monsters take up resources on which ever supercomputer they are located on, as seen with Kolossus since it can only be mobilised by X.A.N.A. with multiple Replikas as sources of energy.
When monsters are mortally wounded or fall into the digital sea, they simply devirtualize. The destruction of their virtual envelope corresponds to their complete disappearance within the virtual world.
Most monsters have the ability to aim their laser, though they do not seem to do so often. This is shown from the monster's point of view, which is dominated by a trisected, white circle. When targeting something, an upside-down, red triangle follows what they intend to shoot. When it locks on, the red triangle centers within the circle and three red lines connect each vertex of the triangle to the circle. Only a few monsters have directly demonstrated this targeting system, but it is safe to assume that others utilize the same system.
Monsters on Lyoko
- Kankrelats: These monsters are X.A.N.A.'s weakest ones. They usually attack in large groups. They are much faster than Bloks, and are fairly hard to hit because of their small stature.
- Hornets: These are the first monsters that are capable of flight, and are one of the few to have more than one attack. They can fire rapid-fire lasers and spray poisonous acid.
- Bloks: They are one of X.A.N.A.'s most used monsters. Bloks have three different attacks, standard laser, rings of flame, and freeze ray.
- Krabs: They are generally found in groups of two or three. They can use their legs to stab their enemies, and fire strong lasers from their eyes. In the second season, they demonstrated the ability to project lighting blasts from under them. This is the only monster that can be destroyed by cutting off its legs.
- Megatanks: These are one of X.A.N.A.'s strongest monsters. They are large and ball-like, whose armor is indestructible. They attack with a powerful laser that can runs straight in all vertical directions. To do this attack, it must expose its Eye under its armor, making it vulnerable in that moment.
- Guardians: They are the hardest monsters to destroy since it has no weak points, Guardians are used to hold someone prisoner inside its indestructible sphere of energy. The only way to destroy one is to trick it into believing that it's holding the wrong person.
- Tarantulas: They were first introduced in New Order, they were depicted as X.A.N.A.'s deadliest monsters. They are excellent shots and are very durable.
- Creepers: They are found in the Carthage Sector. Creepers are snake-like monsters that attack by firing lasers from their mouths.
- Mantas: The strongest flying monsters. They are large manta ray-like creatures with strong lasers. They can fly through the air, but are slower than Hornets.
- Sharks: Only found in the Digital Sea. Shark-like creatures that attack by shooting torpedoes from their mouths.
- Kongres: Found only in the Digital Sea. They have the appearance of giant piranha eel monsters. They are the most common monsters seen in the Digital Sea and have only one laser weapon that is fired from their eyes.
- Kalamar: Found only in the Digital Sea.
- Scyphozoa: One of X.A.N.A.'s most valuable pawns. It has the appearance of a giant jellyfish and is very difficult to destroy. It has the ability to drain the knowledge, DNA, and life force from a victim with its tentacles, and can also implant a virus within its victim, and also possess its mind.
- Kolossus: X.A.N.A.'s biggest and strongest monster ever. Created by drawing computing power from the hundreds of Replikas that it has established all over the Internet. It has the appearance of a giant fire and earth elemental being. Its body is indestructible and one attack from it results in instant devirtualization. The only way to destroy it was to simultaneously attack the Eye of X.A.N.A. on its head and its left sword arm.
Video Game Only Monsters
- Polymorphic Clone
- Kankrelats - in "False Start" and "Hard Luck"
- Krabs - in "A Bad Turn"
|Jeremie Belpois | Aelita Schaeffer | Odd Della Robbia | Yumi Ishiyama | Ulrich Stern | William Dunbar|
|Sissi | Jim Morales | Suzanne Hertz | Anthea Schaeffer | Mr. Delmas | Laura Gauthier | Franz Hopper|
|Kiwi | Herb Pichon | Nicholas Poliakoff | Amelia "Milly" Solovieff | Tamiya Diop | Hiroki Ishiyama | Johnny | Takeo and Akiko Ishiyama|
|X.A.N.A. | Monsters|
|Professor Tyron | Ninjas | X.A.N.A. William|
|Jean-Baptiste Pujol | Theo Gauthier | Emily LeDuc | Taelia | Samantha Knight | Samantha Suarez | Heidi Klinger | Mathias Burrel | Magali de Vasseur | Claire Girard | Brynja Heringsdötir | Patrick Belpois|
| X.A.N.A. Aelita | X.A.N.A. Odd | X.A.N.A. Yumi | X.A.N.A. Ulrich | X.A.N.A. Franz Hopper | X.A.N.A. Anthea Schaeffer | Jeremie Clone | Aelita Clone | William Clone|