Scarlett Sinister is sisters with Sage and Sapphire Sinister. She is an evil witch who tried to take over Halloweentown with her father, Silas Sinister, and the Dominion. She also tried to coax Marnie into using magic, turned Dylan into a dog with her sisters, and hexed Marnie's essay.
Scarlett seems cold and harsh. She is concieted, and used to common attention. When her sisters lost their powers, Scarlett quoted, "Without our powers, we might as well be... UGLY!" She is very proud of her heritige. Boys seem to be in love with her, since they always do magical deeds for her and her sisters. Although most of their feelings is only for her looks, she invite the glances of thoses who also have "looks."
- All of her sisters, plus her father, begin with S.
- Many of her family's belongings have a snake in the shape of an S.
- Sapphire, Sage, and Scarlett rule the school.