Villians, But Can't Help But Love

As the title suggests, these are characters on the antagonist's side. Even through all their terrible deeds, for one reason or another you can't help but love the character. 

A good villain is intelligent, resistant, and not pitiful, they had things happen to them, that made them the way they are, but they still aren't pitiful... at least not completely. They make a perfect foil for the protagonist to challenge them and make them shine. They have a weak spot, they have a part that doesn't necessarily fit with their other actions. Maybe they just killed some one in cold blood, but then save and hurt animal. Maybe they correct a child on swearing, idk. They have a clear reason for being, they aren't JUST evil for evil's sake. Heck they could be the hero of their own story. It's a hard thing to write well, but when it is... *chefs kiss*. Add on to that the work the actor/tresses need to do to make it believable across the screen.
These villains don't just annoy you and they aren't necessarily going to seek redemption, they curl your blood, scare or make you feel uncomfortable, and they remain consistent. This doesn't mean they can't try for a redemption arc, but if they do, make them actually work for that redemption.

Basically the writing is so steady, and the actor/tressess delivered so well, it's an actually well done villain.
And most important for this list, you have to want to watch their scenes just as much as the hero's.

(They also don't have to be a dark villain, an antagonist doesn't even have to be a person... but for the most part, that's who's going to be on this list.)

(Perhaps order of fav... mostly a WIP)

Related Lists
Love-able Dastardly Charlatans

Love-able Dastardly Charlatans = Protagonists/main characters of questionable morals