This is a mug shaped like the Night King.
The Night King is a major villain from the Game of Thrones novels and HBO television adaptation of the same name. The Night King is an icy zombie like figure with blue eyes who has the power to resurrect the dead and has used that power to amass an army with which he intends to take over the world until everything is dead and covered in ice. His origins are shrouded in mystery but it is shown in the HBO series that he was once a man and was transformed into a "White Walker" by the Children of the Forest (an early race of creatures both plant and elf-like) in order to create a protector against encroaching mankind. They never intended the White Walkers to get so out of hand, however, and it is apparent that they were a weapon of last resort gone awry. As the first of the White Walkers, the Night King functions in the story as the most powerful villain (in a series with many villains to root against), akin to Dracula at the head of a vampire army but in this case...ice zombies!
This is one in a series of Game of Thrones ceramic mugs. Many of these same designs were also produced as plastic mugs with straws and lids.