(Spoilers Extended) Which character did the show 'hollow-out' the most?

One of the aspects of the books that separates them from the show the most - in my eyes - is the fact that the characters feel so much richer in the books. There's just so much more to them, even though I'm only reading words about them, they feel so much more real than they ever did on screen.

Some characters suffer more from this in my opinion. I'd say Catelyn, Tyrion and Jon suffer most from this 'dulling down' as I'd call it in the adaptation. But I'd say all suffered somewhat.

Which POV characters would you say suffered the most in this regard?