Two characters immediately sprang to mind when I saw this topic come up on Long and Short Reviews - one from classic fiction and one of my own.
The first is Angel Clare from "Tess of the D'Urbervilles". I read this mainly because it was set in my dad's home village (Marlott in the book, Marnhull in reality). I really did try to like it, but it's a deeply depressing read, primarily because Tess's love Angel Clare is such a hypocrite. The tragic conclusion comes as a direct result of Angel abandoning Tess for something that wasn't even her fault - he rejects her for lack of purity even while at the same time he tries to take one of her friends as his mistress. Oh, how I hate that man.
The other is Reed James from my three-book series "I Heard Your Voice", "Tamar Rising" and "Spiritwalker". Reed James is a celebrity medium, insufferably arrogant and incapable of considering anyone other than himself. I've had people come up to me and tell me they just wanted to give him a slap, which means I did my job, because I want to give him a slap too. He remains unredeemed, as I couldn't find a way to redeem him.
So which characters would you never want to meet?