|Voiced by Travis Ferris|
|Social Status||Former student, Villain|
|Signature Ability||Rotting organic material|
Kid Rot (voiced by Travis Ferris) - In an attempt to make friends, a young, lonely boy named Chester tries to find a way to make sure food never rots. However, something in his experiment went wrong, and Chester gained the "Rotting Touch," with which he causes all organic materials to rot with a single touch, and also gives off a horrible smell. He deeply despises his new powers, labeling himself a monster. He becomes a new student at Ringworm Junior High School, and causes chaos upon his arrival, with a concerned Abby and Ty trying to cure him (Chester developes deep feelings for Abby, much to Ty's suspicion). But Chester's rotting powers literally go to his head, giving him a twisted split personality (even christening himself "Kid Rot"), and making him a formidable and diabolical foe for the Grossology team. His love for Abby grew bigger for her (who ultimately hates him, at least his prevalent Kid Rot persona), and will stop at nothing to impress her and win her heart, even going as far as to rot the entire world. His rotting powers used to be an excellent fertilizer (in a way making his science experiment a success), but the second time they met, his rotting powers had evolved to the point where they can kill whatever they touch. The last time we saw Chester, he was engulfed in rot. Abby and Ty gave up looking for him but as the episode is about to end you see a hand (Kid Rot's) sticking out from the rot and as a leaf lands on it, its grabbed by the hand, followed by heavy breathing. We have yet to know what has become of Kid Rot.
- Real Name: Chester
- First Appearance: Episode 13 ("Kid Rot")