Lisa Simpson as an adult villainess
Baby Lisa Simpson (Yeardley Smith) is a villainess from "Smart And Smarter", episode 15.13 of The Simpsons (airdate February 22, 2004). The episode had Maggie being declared a genius after scoring high on several tests in a kindergarten, much to Lisa's jealousy.
The little girl was eventually driven to attempt to sabotage her baby sister, only to be caught by their parents who scolding her (causing her to run up to her bedroom in tears). That night, Lisa had a nightmare where she was an adult woman who was the wheelchair-bound Maggie's caregiver (a parody of the film Whatever Happened To Baby Jane?).
The nightmare began with the evil woman brushing her hair in front of the mirror (bitterly lamenting how she used to be the smart one in the family). When an adult Maggie entered the room to ask where her food was, the psychotic Lisa turned heel by taunting her younger sister and saying she would "learn how to fly". Although the disable woman pleaded her older sister to spare her life, the jealous woman threw her down a flight of stairs to her death, with the madwoman cackling maniacally after committing the murder. Lisa then woke up, leaving her psychotic adult self's fate unknown.