Dagmer

Dagmer is a recurring character in the second season and debuts in "The Ghost of Harrenhal." He is played by Ralph Ineson. Dagmer is a noted ironborn reaver. He is known by his nickname Dagmer Cleftjaw because of a scar across the angle of his jaw on the left side of his face.

Background
Dagmer is an ironborn raider and reaver, noted for his skill in battle and his loyalty to House Greyjoy. He is called Dagmer Cleftjaw for the scar he bears across the left side of his jaw.

Season 2
Dagmer emerges from the tavern and offers to take Theon to their ship, the Sea Bitch. Theon asks who he is and Dagmer explains that he is to act as Theon’s first mate. Theon questions Dagmer being separated from the rest of the crew and wonders if they have sent Dagmer to kill him when they are on their way to the ship. Dagmer says that the men will not respect Theon until he has proved himself. Theon wonders how he can prove himself when his father has ordered him to attack fishing villages on the Stony Shore. Theon asks Dagmer how he can prove himself a true iron islander with such a task. Dagmer tells him that his crew are all iron islanders and asks Theon how they respond to orders. Theon sees the wisdom of Dagmer’s words and suggests that Torrhen’s Square lies near to the Stony Shore. Dagmer says that the seat of House Tallhart is a worthy prize as Theon contemplates his idea. Dagmer wonders if Theon doubts their ability to take it. Theon says that they could but would only be able to hold it for a few days. He explains that Winterfell would hear of their victory and then House Stark would send men of their own to take it back. Theon considers this opportunity and then instructs Dagmer to take him to his ship.

Theon besieges Torrhen's Square and then strikes at Winterfell once it has been left poorly defended. He seizes the castle and forces Bran Stark to yield to him by threatening his people. Lorren captures Ser Rodrik Cassel as he returns from Torrhen's Square. The master-at-arms is defiant and spits in Theon's face. Dagmer insists that Theon must have him executed to maintain the respect of the crew. Rodrik baits Theon into swinging the sword himself and Theon fumbles the task, requiring four blows to sever his head.

Osha seduces Theon and frees Prince Bran and Rickon Stark. She murders Drennan while escaping the castle. Dagmer and Theon discover the corpse the next morning. Lorren blames Theon for being seduced and Theon brutally beats him as Dagmer looks on with approval. They go out to hunt for the boys with hounds and track them to a shepherd's farm before losing the scent. Dagmer finds cracked walnut shells at the farm, a favorite food of Rickon. Theon brutalizes the shepherd who insists that he has not seen the Stark princes. The Ironborn return to Winterfell with two charred corpses that Theon publicly claims are Bran and Rickon.

In the books
In the Song of Ice and Fire novels, Dagmer Cleftjaw is the captain of the Foamdrinker and is remembered fondly by Theon Greyjoy from his childhood. Dagmer is a solid and dependable commander, but has been known to take gambles if he believes the reward is great enough. A longaxe blow shattered his jaw as a child, leaving him with four lips rather than two and an enormous scar, the source of his nickname. He is the master-at-arms at Pyke.