This is a hard one, so I'm glad it's you that asked because you won't mind a tangent.

There's a lot of variables here, but my favourite overall character is Blue Jones.

I like him because he's eccentric, unique, he's got style and pizazz whilst being the main antagonist. But a key part that places him as my favourite is he had depth. He's not simply "Evil pimp that hates women", he's got more character than that. Blue can be described perfectly as someone who loves control but cannot control himself. He wants control over his environment, the staff, the patient's, how the place runs, wants his name instilled in everyone's heads. Oscar Isaac said in an interview that the brothel dream version of Blue wasn't Babydolls version of him, it's also how Blue saw himself.

We can see Blue, as a person in real life, is a weasel, not well liked, not commanding respect because of who he is but because of fear, because of how position of power. He's got dark bags under his eyes, plain orderly uniform, just a shitty guy that happens to be in power somewhere. Club Blue is not that, he has eyeliner to replace his eyebags, a stylish tache, slicked back hair, sparkly bright suits, a dance routine, he sings and dances, he has glamour.

The end is a perfect wrap up for his character. Despite how much he prided himself on having everything under his thumb the girls managed to almost fully complete an escape mission under his very nose and now he's losing control, the one thing he has and craves. And his punishment to Babydoll for that ends up taking away that too. The lobotomy takes her from him, and when she can't fight back, there's nothing there for him to control.

"You're here with me, in all this shit." He knows his place in the asylum is fucked, he doesn't enjoy the place itself and yet it's clearly all he has and when he loses it, it's enough to send him into frustrated tears.