Karen McCormick
| Gender | Female |
| Age | 6 |
| Hair Color | Dirty-Blonde |
| Occupation | Student |
| Grade | 1st Grade |
| Religion | Roman Catholic |
| Father | Stuart McCormick |
| Mother | Mrs. McCormick |
| Brother | Kevin McCormick |
| Brother | Kenny McCormick |
| Grandfather | Grandpa McCormick |
| Voiced by | Celeste Javier |
| First Appearance | Best Friends Forever (background) The Poor Kid (speaking) |
Karen is Kenny's rarely-seen little sister. She often clings to her brothers Kevin and Kenny for support. She likes playing with dollies and visiting North Park Funland.
When her parents were taken away and they were assigned to a foster family, Karen had trouble adjusting and missed her parents despite their fighting. She stayed close to her brother, and was protected by her mysterious guardian angel. She clung to her older brother, Kevin, when Kenny was in the hospital.
She bares a resemblance to Heidi Turner.