ruthless and aggressive, now trying to destroy Lyoko to make the team powerless against it (succeeded at the end of the third season, but was recreated after) and possessing William to become its weapon. After that, X.A.N.A. also targets Franz Hopper, the biggest threat and the reason why the group keeps surviving. At the same time, the heroes discover X.A.N.A. has infected hundreds of other supercomputers in the network to build weapons and technology to conquer the world. Near the end of the series, the group manage to free William and although it succeeded in killing Franz Hopper in the final battle, the team successfully destroyed X.A.N.A. everywhere in the network with Jeremy's multi-agent program, but only for a time. Monsters X.A.N.A. can program many types of monsters on Lyoko to fight, guard Towers, or attack important targets. The monsters generally appear to be organic/mechanical creatures based on various animals and insects. X.A.N.A.'s monster types include Kankrelats, Hornets, Bloks, Krabs, Megatanks, Tarantulas, Creepers, and Mantas. These monsters can be destroyed by hitting the Eye of X.A.N.A. on their bodies. In the Digital Sea, it uses monsters such as Kongers, Sharks, and the Kalamar. It also created the Scyphozoa, which it uses to steal data, drain energy, or brainwash warriors. There is also its ultimate monster, the Kolossus, which appeared in the last three episodes and is fueled by the combined power of its network Replikas. In the videogames, some monsters are exclusive to fight such as Cyberhoppers, Skarabs and Skorpion from Get Ready to Virtualize, Insekts, Volkanoids, Mountain Bug, Insekt Lord, Ice Spider, Desert Driller and Magma Worm in Quest for Infinity and Fall of X.A.N.A., other varients are called "Dark Monsters" which are equipped with different abilities when in combat. Recurring characters Elisabeth "Sissi" Delmas Voiced by: Carole Baillien (French); Christine Flowers and Jodi Forrest (English) The principal's daughter and a Kadic student. She is a mean, spoiled, conceited, but also beautiful and somewhat popular girl who has had a huge crush on Ulrich since before attending Kadic. Sissi and Odd quite often make fun of each other, with Odd making clever comebacks whenever Sissi says something rude or whenever they need her to go away. After Aelita is first materialized, she often does the same. Sissi tends to make fun of and openly insult Yumi in particular, mostly due to Ulrich liking Yumi more than her. Sissi is