Harald Karstark

"The Starks lost my house the day King Robb cut off my father's head. It's time for new blood in the North."

- Harald Karstark to Roose Bolton

Harald Karstark is a recurring character in the sixth season. He is played by Paul Rattray. After the deaths of his brothers and the execution of his father, Lord Rickard Karstark, by Robb Stark, Harald is the new head of House Karstark and Lord of Karhold. He is described as ruthless and calculating.

Background
Harald is the son of Rickard Karstark and younger brother of Harrion and Torrhen Karstark. Following the deaths of his two brothers earlier in the war, and then his father's execution at the hands of Robb Stark for treason, Harald becomes the new head of House Karstark and forsakes his allegiance to Robb, leading the Karstarks back to Karhold.

Season 6
Harald appears before Lord Roose Bolton and Roose's son Ramsay Bolton at Winterfell, reporting that his men had found the remains of the Bolton hunting party that was sent to track down Sansa Stark and Theon Greyjoy. Harald counsels Roose that, despite being a bastard, Jon Snow, as Ned Stark's last surviving son, presents a threat to the Boltons' rule of The North. He affirms his house's loyalty to House Bolton, saying that he will never follow a Stark after King Robb's execution of his father, Lord Rickard Karstark. When Maester Wolkan arrives to announce that Walda Bolton has given birth to a boy, Harald congratulates Roose. However, despite the fact that Roose avenged his father by killing Robb, Harald shows no surprise and makes no attempt to intervene when Ramsay kills Roose shortly afterward. He even chastises Wolkan for failing to address Ramsay as "Lord." He also makes no effort to dissuade Ramsay from murdering Walda and her baby, even though their deaths will most likely spark a conflict with House Frey, the current Great House of the Riverlands.

Harald and Ramsay meet with Smalljon Umber, the new Lord of Last Hearth. Harald notes that the Umbers are loyal to House Stark, but Smalljon retorts by noting that the Karstarks share blood with the Starks, yet Harald is now pledged to Ramsay Bolton. Harald casts doubt on the possibility of the wildlings taking Winterfell, but Smalljon says that, with Jon Snow in command, it would be possible. When Smalljon brings in Osha and Rickon Stark, he claims that Harald has an interest in young boys, angering him.

In the books
In the A Song of Ice and Fire novels, there is no "Harald Karstark" - the TV character is apparently a condensation of different Karstark characters from the books.

In the novels, Lord Rickard Karstark had three sons: his eldest son and heir Harrion was captured after the Battle of Duskendale, while his other two sons Torrhen and Eddard were killed in the war. Rickard also has a daughter named Alys. The TV series changed this around somewhat: instead of Torrhen and Eddard dying, it is stated - by name - that "Harrion" and "Torrhen" died, and no mention is made of Eddard Karstark - possibly to avoid the confusion of introducing another character named "Eddard" after Eddard Stark (Martin intentionally re-used first names for several characters because he thought it would be contrived if no one had the same name in an entire continent).

Due to the actor's young age, "Harald Karstark" in the TV version seems to be a condensation of Arnolf and Harrion from the books: Arnolf's status as the new ruler of House Karstark who is more willing to tolerate Bolton rule, and Harrion's status as Rickard's surviving son - thus saving the screentime it would have taken to introduce the internal politics of House Karstark from the book version.

After Robb Stark executes Lord Rickard in the novels, the Karstark forces abandon him and return back to the North - and because Harrion is still a Lannister prisoner, Rickard's uncle Arnolf becomes acting head of House Karstark. Because the Karstark army did not remain in the south, it was not present at the Red Wedding to be destroyed along with the rest of the Northern army. This makes the Karstarks politically important in the post-Red Wedding North, as they are the only major Northern House (other than the Boltons) with their standing army still relatively intact - thus the Lannisters want to ensure that they maintain political leverage over them. Even after the Red Wedding, therefore, Rickard's surviving son and heir Harrion continues to be kept prisoner by the Lannisters - a tacit arrangement with Arnolf, who is much more willing to have House Karstark tolerate Bolton rule over the North when his new status as leader of his family is dependent on the Lannisters not releasing his great-nephew from captivity.

Arnolf is introduced in the fifth novel. He is not a lord but the castellan of Karhold, though he's referred to as "Lord Arnolf" as a courtesy - similarly to how Varys or Tyrion Lannister are addressed as "Lord" despite not holding any lordships. He is described as thin and twisted, one of his shoulders is much higher than the other. His eyes are grey and greedy, his teeth yellow, his forked beard a tangle of snow and silver. Only a few wisps of white hair still cling to his spotted skull. He wears a cloak of grey wool trimmed with black sable and fastened at the shoulder with a starburst wrought in beaten silver. According to Jon, Arnolf has never been, even in his youth, the fighter Rickard was. Theon, who saw Arnolf briefly at Dreadfort, considers him as "a poor excuse for a man".

In the books, Harrion was taken captive by the Lannisters in the Battle of Duskendale. He was imprisoned in Maidenpool, but it has been almost a year since his surviving kin received news about it, and it is uncertain if he is still alive. It is unknown if in the books he was still loyal to the Starks after his father's execution: Robb was certain that would turn Harrion against him, because "the North remembers", even though the execution would make Harrion the lord of Karhold. Indeed, the show character Harald reacts the way Robb predicted Harrion would.

The books reveal how Harrion's sister Alys, also disinherited by Arnolf's new rule, feels about Robb for killing her father: she resents him, stating "I thought the whole reason they marched south was to kill some Lannisters". She knows for what crime her father was executed, but it does not make a difference for her. But, since Jon belongs to the Night's Watch, there is no blood feud between them, and she asks his help to save her from her great-uncle, who plots to force her to marry his son so that he can claim Karhold legally.

In the television series, Smalljon Umber quips that Harald "likes young boys". So far in the novels, there is no mention that any member of House Karstark is either homosexual or a pedophile.