Louise Fletcher was an awesome lady. Here's part of her Oscar speech after she won for playing Nurse Ratched:
Well, it looks like you all hated me so much that you've given me this award for it, and I'm loving every minute of it. And all I can say is I've loved being hated by you.
She was an incredibly talented lady, especially at playing insufferably hateable characters. She only died two years ago. Supposedly in real life, she was a sweetheart.
I really enjoyed despising Kai Winn. She’s such a broken character, always choosing the wrong side and still being completely convinced that her way is without alternative.
Still, I had some level of empathy with her (the gods she, in a way dedicated her love to, never chose her, never spoke to her and when she finally received visions, it was demons deceiving her). Fletchers performance is just the best.
I think because she seems to real and believable. You look at it and think "wow this could be a politician/religious authority IRL. I've seen people like this."
It's kinda like how if someone kills someone on TV you don't think much of it because it's not something most people can really relate to. If you see someone cheat on their partner, though? It fills you with rage because for a lot of people, it's relatable and it hits close to home. She's a real-world villain.
Gul Dukat = villain you hate that you kinda love
He's constantly switching from very obviously evil to seemingly redeemable. You even see some qualities of him that are really good - he clearly cared about his daughter, and on more than one occasion he was extremely quick to change his mind and say he was wrong, something even good people struggle with. And he just has this ridiculous charisma.
Then you feel shitty when he snaps and goes full mask-off evil, guilty for falling for his charisma and ever thinking he could turn good.
I haven't even spoken about the Founders, Vorta, and Jem'hadar, they were all great too. Man DS9 had fantastic bad guys.
She's like the dude from the Voices Carry video. Every frame they appear in makes you want to push the Earth into a black hole just because they are on it.