To steer this thread in a slightly different direction, what are some characters you feel that were actually
improved in the show? Catelyn for sure. I searched for an old post of mine when I finished reading ASOS and was surprised to remember how much i disliked her.
I actually liked her a great deal in the show, Michelle Fairley really hit it out of the park and made the character her own. King Robert in S1 is another one, he was almost a non-entity in the book.
I'm going to answer this by suggesting characters I feel are improved as characterizations on the show by the way the decided to depict the character and how the actor elevates the role. It doesn't mean I -like- the characters, but rather, I like the way they are handled.
Theon - I hate Theon on the show. He's a pile of shit, a loser, and the actor has this amazing ability to make him look so much more pathetic than he should in every scene. But that's what I *love* about it. He's always funny to watch, and he made many episodes in Season Two worthwhile just because his goofy pathetic nature seemed so real and so sincere. In the books, I found him a chore to read. In the show I actually look forward to his scenes, maybe not so much in Season Three because I'm not a fan of torture porn.
The Hound - I love his character in the show, and I think they've done a fantastic job with his character arc. The actor brings great presence to his scenes, and I think they do a good job with showing his conflicted emotions without having him say much at all. I think he single-handedly saved many of Sansa's King's Landing scenes, because her actress never did much for me, and even her interactions with Littlefinger weren't very interesting to watch. But the few interactions between her and the Hound really had a strong positive impact. I'm loving his scenes with Arya now too.
Gilly - I was pretty surprised by this one, because in the books I felt she was very much just a convenient part of Sam's narrative. The girl he runs into, and he helps, and in doing so helps him learn how to be more of a man. Sure, it's more or less the same here, but the actress is doing a really good job of playing off Sam's, and there's a real chemistry there. I find her very charming and it really helps make good scenes even better.
Joffery, Tywin, Tyrion, Ned, Mel, Arya, etc are all great characters on the show and very well acted, but they already had fantastic material to work off of, and honestly I liked (or hated) reading their book counterparts just as much as I do watching the versions on the show.