One of the most powerful of the Northern lords, Roose Bolton is known for speaking very softly, but this does not mean he is gentle. He is cold-blooded and extremely pragmatic; as an example, he urged the immediate execution of the severely wounded Barristan Selmy following the Battle of the Trident, which suggestion Robert Baratheon overrode. Ruling the Dreadfort, he has no legitimate offspring but does have a bastard son that he has acknowledged and is raising, Ramsay Snow.
Another excellent casting choice, at least as far as physical appearance goes. His eyes do not seem as pale as Bolton’s extremely pale eyes, a detail often mentioned in the novels.