Royce IV Bolton

King Royce IV Bolton, also known as "the Redarm" is an unseen character in Game of Thrones. He was a Red King and head of House Bolton.

Biography
Royce earned the nickname "the Redarm" due to his fondness of his arm into the belly of captive Starks and pull out their entrails with his bare hand.

Reference

 * "Northern Allegiances to House Stark"