Suggestions by @graceless

Gillian Anderson

as Max Eisenhardt in Marvel Comics (Gender Swap)

Score: +7

Jessica Barden

as Rey in Star Wars

Score: -7

Tuppence Middleton

as Pietro Maximoff/Quicksilver in Marvel Genderswap

Score: +1

Jessica Chastain

as Medusa in Fantastic Four

Score: -1

Michael Fassbender

as Vincent van Gogh in Celebrity Biopics

Score: +7

Emma Stone

as Miss Martian in Young Justice

Score: -13

Emeraude Toubia

as Zatanna in Young Justice

Score: +2

Charlize Theron

as Kaa in Disney Villains

Score: 0

Eva Green

as The Evil Queen in Disney Villains

Score: +75

Sarah Gadon

as Narcissa Malfoy in Marauders

Score: +1

Boyd Holbrook

as Lucius Malfoy in Marauders

Score: -11

Rose Leslie

as Wendy Corduroy in Gravity Falls

Score: -8

Ella Purnell

as Mabel Pines in Gravity Falls

Score: -11