Zombies is a term used for a X.A.N.A.-possessed human. It is generally used in place of "X.A.N.A.-Name" when it is a group of people or someone who is not commonly possessed (like background characters). Zombies were first seen in Ghost Channel where X.A.N.A. imprisoned Yumi, Odd, and Ulrich in a simulation bubble and could make zombie-fied verions of characters from Kadic at will.
Zombies were next seen in Attack of the Zombies where Kiwi was possessed and bites people to turn them into zombies. Zombies have their own way of turning people into them by biting; although this is never seen but is proven. The only people that were not zombie-fied were Ulrich, Yumi, Aelita, Sissi, Milly, and Rosa, the Kadic chef. Zombies have altered voices that sound malevolent in nature. Tamiya was the first victim and Jeremie was the last. Jeremie was able to resist the effects long enough to launch a return to the past.
Code Lyoko's zombies are generally identifiable by grayish skin, emaciated faces, sharp teeth, sharp nails, and pupil-less, glowing eyes. In Code Lyoko's zombies, the time to transformation is a few seconds. Zombies are a popular element of western popular culture in the horror genre.