Welcome to another 30 day challenge which in honor of spooky season will cover the topic of Pop Culture Villains!

Oftentimes, a villain is closely linked to a heroic character. Sometimes, they’re linked so closely that they share a body! This obviously covers your Jekyll/Hyde archetypes, but also all manners of possession, and the beloved anime trope of having a big ol’ demonic force sealed inside you for occasional powerups/berserker states.
So the main prompt of today is: What are are your favorite examples where a villain/villainous side is just one facet of a character, vying for control? Do you enjoy this trope at all?

Bonus Prompt: Best and worst representations of Two-Face

Maniacal prompt: Best and worst cases of “actually there was no split identity, I was just 100% evil!”?

Machiavellian Prompt: Best and worst cases of “Actually I wasn’t evil, it was this other personality/evil force doing the evils!” retcons?

Nine tailed demon fox prompt: best and worst cases of complete separate-entity inner evils?