It may not be the first thing fans think of, but the problematic relationship between life and death plays a considerable part in Game of Thrones. As Houses go head-to-head in the deadly political struggle of the Seven Kingdoms, winter brings a dark and ancient threat from the north. The leader of the White Walkers, the Night King, is a zombie-making machine, but A Song of Ice and Fire makes sure there's a warm balance to his cold threat.