Quenley Woosterfield is the devious half-sister of Simon Woosterfield.
She attempted to kill Simon along with her brother, Devan Woosterfield, on a ski trip. She proves to be the most greedy of the Woosterfield kids, as she was presumably going to kill Devan after killing Simon to get the family fortune to herself. She is considerably more devious than her brother, Devan. Milhouse claimed he liked Quenley, getting over the fact Bart's real sister didn't like him back anyway.
- Quenley and Devan were presumably British, due to their possessing British accents.