Stephanie

Stephanie Gavin is a supporting antagonist in World of Timmy, and the main antagonist in the spin-off show, Stella and Friends. She is a 16-year-old girl who is extremely mean to Timmy and his friends, especially Stella. She is always plotting to get Stella (and sometimes Timmy) in trouble, an infamous example being Stella Gets Expelled where she creates a realistic Stella robot and uses it to vandalize the girls' bathroom.

Trivia

 * Stephanie, like every other antagonist in a popular show (such as Megatron, Devious Diesel, and Santed Sailor), gets a lot of grounded videos made out of her on Vyond (GoAnimate).