|“||Every time you block us, we get smarter. Every time you try to stop us, we are more. If one plan fails, we will plan another. You will never be rid of ads.||„|
|~ Leslie's last words|
Leslie Meyers is the true main antagonist of South Park's ninteenth season. She is a living advertisement sent out to destroy South Park for an unknown group.
At first she seemed like a normal talkative fourth grader who always found herself at the receiving end of PC Principal's anger do to talking during his speeches about social tolerance. But it's revealed she is "special"; a living advertisement. Her existence is to make sure advertisements take over the world. Leslie is willing to fake kindness, manipulate, and hurt others (as shown with Jimmy) to make sure she succeeds in her plan of world domination comes to fruition.
Throughout the first seven episodes of Season 19, a recurring gag would show Leslie being repeatedly called out by PC Principal from time to time for talking to other students, even if she wasn't even speaking to them in the first place.
However, for the last three episodes of Season 19, she is set to be the Bigger Bad of the Season. In Naughty Ninjas, after Officer Barbrady was fired yet again, he joins the newsmen to uncover a sinister secret about Leslie. In Sponsored Content, Jimmy was being tested by newsmen for his unique ability to distinguish what is an ad and what is not, after Barbrady protected Jimmy from a shady GEICO salesman. During the trials, Jimmy is then tested to have a talk with Leslie. To Jimmy's horror, after having his first conversation with her, he finds out she is in fact, an ad.
Her true colors are unveiled in Truth and Advertising, when Jimmy did everything he could to tick Leslie off to uncover what she has planned. After finding out what would happen to enemies like her, Leslie distracts the observing newsman with an ad during her last interrogation with Jimmy before deciding to escape with him. However, the newsmen get mad at Jimmy, since they believe he is listening to his dick, rather than to reason. Officer Barbrady lets them escape, since he was not willing to shoot another child, despite being ordered to kill them for turning their backs on them. Jimmy and Leslie then storm right into school newsroom, where Nathan was put in charge by PC Principal, after firing Jimmy in the previous episode, due to his actions, such as labelling his PC crowd "pussy crushers". While trying to confront Nathan about the lies of advertising, Leslie double-crosses Jimmy by brutally beating him up and then orders Nathan to finish him off. At the end of the episode, she requests Kyle Broflovski's help and his social security number, before running off with him.
In the season finale, PC Principal Final Justice, Leslie manipulates Kyle to defend her and turn him against Stan, Randy, PC Principle while she sets her plans into motion behind his back. She was able to trick the Army that arrested PC Principal by pretending to be President Obama into letting him go with a catch. However, PC Principal finds out about her actions and behaviour, and calls her out, like he usually does in Season 19. Leslie claims that ads cannot be stopped and will always find ways to get around ad-blockers. PC Principal then proceeds to expel her from school, before punching right through her face in retaliation for being used as a red herring, thus, killing her off and putting an end to her schemes.