M-O (Microbe-Obliterator) is one of the two tritagonists in WALL•E. He is a robot aboard the Axiom programmed to clean items deemed contaminated. M-O is obsessed of keeping things exempt of "Foreign Contaminant", and can do anything to complete this task (an example and running gag is when WALL•E teasingly wipes the dirt off one of his treads and covers M-O's face with it, he screams and frantically tries to clean his own face!) He travels around on a single roller, equipped with cleaning tools.