What is the name of Kenny McCormick's younger sister?

Kenny McCormick's younger sister is named Karen McCormick. She is the youngest of the McCormick children and is portrayed as especially close to Kenny.

Karen first appears with the McCormick family in the season-nine episode “Best Friends Forever,” but her name is revealed later in the season-15 episode “The Poor Kid.” Kenny is protective of her, and she views his superhero identity, Mysterion, as a guardian figure.

Karen's family background is shaped by the McCormicks' poverty and instability. Her parents are Stuart and Carol McCormick, and her older brother is Kevin. The family is also central to South Park's dark running joke about Kenny repeatedly dying and returning.

Viewers sometimes confuse Karen with Ike Broflovski or Shelly Marsh, but neither is Kenny's sibling. Karen is also distinct from Kenny's older brother Kevin, whose name appears in the same family listings.