Kankrelats, referred to as Roachsters in the first season, are the smallest and weakest of Xana's monsters, being light enough for the warriors to kick around. They are fairly fast when they want to be, and are excellent dodgers thanks to their small size. They can also leap a considerable distance through enough speed and cling to objects with their pointed feet. The weak point of a Kankrelat is the Eye on its carapace. They are the least intelligent of Xana's monsters.
Kankrelats are equipped with a weak laser cannon below its carapace which causes only 10 points of damage per hit, the weakest of any monster. It also cannot be fired rapidly, so Kankrelats have to employ the same mass-fire techniques as the Hornets in order to be effective. A small spinning laser effect, which represents the weapon charging, precedes the firing. The Kankrelats occasionally run with their lasers pre-charged.
Kankrelats were the first monsters materialized in the real world. Reflecting their power, their laser blasts only burned through clothing but caused average harm. Kankrelats were also the only monsters teleported to the site of a Replika's supercomputer to attack the heroes, during the episode "Hard Luck".
Kankrelats usually move in groups of five to make up for their poor individual power. They will single-mindedly chase their target, regardless of where that target goes to evade them or what dangers happen to be in their way. They will also attack a target relentlessly, regardless of how futile such an action may be in some circumstances. They will occasionally attack from multiple fronts, but usually attack from a single direction.
From the second season onward, the Kankrelats have become the comic relief on Lyoko. In "Attack of the Zombies", a Kankrelat tried to chase Aelita into a tower, only to bounce off of the surface and fall on its side. It then proceeded to run in a circle without getting up. In "Ultimatum", three Kankrelats fall down an ice tunnel in a "Three Stooges" fashion. The first one stops in time to look down the tunnel, the second bumps into the first, and the third crashes into them, causing all three to fall into the tunnel, blasting randomly (and hitting each other) as they do. In the episode "Double Trouble", one of Xana's clones causes bugs in Odd and Yumi's profiles, leaving them immaterial on Lyoko. Despite the fact that their lasers pass right through Odd and Yumi, the Kankrelats continue to fire pointlessly for some time, eventually stopping and just circling their foes, passing right through them occasionally. Throughout the final three seasons, Kankrelats also tend to become the brunt of the warrior's physical jokes, such as being kicked around by Ulrich in "Tip-Top Shape" and Odd in "Double Trouble". Finally, they share the misfortune of being devirtualized by ally monsters when a shot intended for a warrior misses.