Scarlett Sinister is an evil witch attending Witch University and one of the daughters of Silas Sinister. She acts as the ringleader. She secretly defies the "No Magic" rule by using their powers whenever there is no teacher watching. She works with a few professors and her father to make Marnie open a box with the Cromwell family's ultimate magic in it. In the end, her plan backfires and she loses her family's magic as punishment for her father's actions. She is played by Kristy Wu.