Villains Can Be Good!

I've been reading Under the Dome for quite a while now (finally within a normal novel's length of the end) and as always I have great admiration for what Stephen King accomplished. I was thinking today, though, about the main villain in the book. I don't want to give anything away to those who haven't read it, but suffice it to say that he is one bad dude. There is nothing I can think of I would consider redeeming about this guy, and it made me wonder why King wrote him that way. On thinking about it, the situation created is unique and can sustain this type of villainy whereas in almost any other case a bad guy of this magnitude would have been shut down before he began. I started thinking then about what makes for a well-rounded bad guy. Say what you want about Big Jim Rennie, but he certainly isn't a well rounded character.

I thought then about some of my favorite antagonists (note NOT villain) from literature, film, and in one case TV: Javert from Les Mis, Sweeney Todd, The Beast from Beauty and the Beast, Fagin from Oliver Twist, Darth Vader, Ben from Lost, Hannibal Lecter (specifically from Silence of the Lambs), Hans Landa from Inglourious Basterds. What makes these antagonists well-rounded, interested characters vs. flat out evil such as Ursula from Little Mermaid, Jafar from Aladdin, Randall Flagg or Big Jim Rennie?

I realized it's all in the comparison to other characters. Each of those in the first list have a counter-balance to their wickedness that gives them an additional layer in the comparison. Javert is ValJean's antagonist, but Thernadier is evil. Sweeney Todd does terrible things, but Judge Turpin is far worse. The Beast kidnaps and menaces - but Gaston who shows the same negative traits that punished the beast in the first place never changes; The Beast does. Fagin is a pitiable character and shows genuine affection for those in his care -- as opposed to Bill Sikes who is violent (directly opposed to Fagin's moral compass) and far more menacing. Darth Vader redeems himself through his son as opposed to The Emperor who never veers from his course. Ben's manipulations have been shown to be overshadowed by the manipulations of the Man in Black (or maybe Jacob - that's yet to be seen). Hannibal's intelligence and cunning make him far more interesting than Buffalo Bill. Hans Landa's evil is mitigated by the fact that he's working for Hitler.

Maybe there's something to this. The counter-point of villainy - having another character who is more two dimensional than your "main" villain might actually be a good thing in helping to define your central antagonist. Of course, having purely evil characters isn't necessarily a bad thing if it serves the story well, but to develop a well-rounded character the balance against someone MORE evil (as opposed to my previous thought on being a balance against the hero) might service the story even better.

Can anyone think of a well-rounded villain that disproves this theory?