The master-at-arms at Pyke and captain of the longship Foamdrinker, Cleftjaw is named for the horrific scar that nearly splits his face, making his smile a disconcerting and ugly thing. Now old, his name is still feared. He personally taught Theon Greyjoy before he was taken away as a hostage to Winterfell, and Theon calls him “uncle”. The actor cast in the role is much younger than the actual character in the novel, clearly is not playing as if he and Theon know one another, and his horrific scar has been reduced to something much less significant.
It is later revealed by Ramsay Snow, the son of Lord Bolton, that the ironmen who surrendered to him were killed, contrary to the promise of amnesty.