Torrhen Karstark

Torrhen Karstark is a minor character in the second season. He is played by Duncan Lacroix and only appears in "A Man Without Honor." Torrhen Karstark is a son of Rickard Karstark, Lord of Karhold and head of House Karstark. He is fighting alongside his father for King Robb Stark in the War of the Five Kings. He is killed by Ser Jaime Lannister during an escape attempt.

Season 2
Torrhen Karstark is assigned to guard the prison of Ser Jaime Lannister and Ser Alton Lannister. After Jaime kills his cousin, Torrhen enters the cell to check on the two. Jaime then chokes Torrhen with his chains and escapes.

After Jaime is recaptured, Lord Rickard demands the head of the Kingslayer in revenge.

In the books
In the Song of Ice and Fire novels, Torrhen Karstark is the second son of Lord Rickard, and also joins his father and brothers, Harrion, the eldest, and Eddard, the youngest, as part of the Northern forces in the War of the Five Kings. However, he's killed by Jaime during the Battle of the Whispering Wood alongside Eddard.