House Karstark

House Karstark of Karhold is a vassal house that holds fealty to House Stark of Winterfell and briefly did so for House Bolton of the Dreadfort after the Red Wedding due to Robb Stark executing their lord, Rickard Karstark, for treason during the War of the Five Kings. Their lands are northeast of Winterfell, located in heavy forested lands overlooking the Shivering Sea. Their stronghold is a castle called Karhold and the head of the house is the Lord of Karhold.

The Karstark sigil is a white sunburst on black. Their house words are "The Sun of Winter."

Background
House Karstark is a cadet branch of House Stark and trace their descent from Karlon Stark, and through him, to the Starks and the First Men. Karlon Stark was a younger son of the King in the North who was awarded lands on the eastern region of the North after putting down a rebellion of House Bolton of the Dreadfort, about a thousand years ago. Over time, Karlon's seat, originally known as Karl's Hold, became known as Karhold, while the Karl's Hold Starks became known as Karstarks.

Season 1
When Robb Stark calls his banners to march south to rescue Eddard Stark, House Karstark is among them. Harrion Karstark dies in a battle.

Season 2
During Robb's campaign in the Westerlands, he takes with him an army of 6,000 cavalry. Half of this army is made up by Karstark cavalry. Later, Ser Jaime Lannister briefly escapes after killing his guard Torrhen Karstark, Harrion's brother. When Jaime is recaptured, he is accosted and nearly lynched by several Karstark soldiers, incensed by Torrhen's death. After arguing with Torrhen's father Rickard Karstark, Catelyn Stark releases Jaime and tasks Brienne of Tarth with delivering him safely to King's Landing, hoping to secure the release of her daughters, Sansa and Arya. When Catelyn explains this to Rickard, he angrily reminds her of the loss of his sons and accuses her of treason because her own children are prisoners, adding he would gladly offer his life to the gods if they would let his son live again even if that meant living as prisoners.

Season 3
As an act of revenge against House Lannister, Lord Rickard Karstark, the Lord of Karhold, breaks into the dungeons of Riverrun and murders Martyn and Willem Lannister, without the permission of Robb Stark, the King in the North. Robb executes Lord Karstark and the members of his household who assisted him under charges of treason. When Robb asks Karstark if he has any last words, he replies with "You are no king of mine" and is beheaded. Afterward, Lord Rickard's retainers abandon Robb's cause, greatly reducing the size of the Northern army. Because of this the Karstarks, along with the Boltons, have their armies intact following the Red Wedding.

Season 6
Harald Karstark, the new Lord of Karhold, reports the deaths of the hunters sent by Ramsay Bolton to trap the fugitive Sansa Stark. He nods in agreement when Ramsay suggests to his father Roose Bolton that they attack Castle Black and kill Lord Commander Jon Snow, a plan which Roose outright rejects out of fear that it would unite all northern houses against House Bolton. When Ramsay points out that they only need the support of Houses Umber, Manderly and Karstark, Lord Harald assures the Boltons that House Stark lost the Karstarks when King Robb executed his father Rickard, adding that it's time for new blood in the North. Harald keeps quiet as Roose warns his son about the dangers of having the reputation of being "a mad dog" and then congratulates Lord Bolton after Maester Wolkan announces the birth of Roose's son by Lady Walda. Harald watches impassively as Ramsay approaches his father, murders him and orders Wolkan to send ravens to the other northern houses announcing Roose has been poisoned by the enemies of House Bolton. After Wolkan acquiesces, Lord Harald chides the Maester to be respectful to his new Lord.

Harald is present when Smalljon Umber, the new Lord of Last Hearth, forges an alliance with Ramsay by presenting the captives Osha and Rickon Stark. Smalljon quibs that Harald has an interest in young boys, which visibly angers him.

During a war council at Castle Black, Davos Seaworth confirms what Ramsay said earlier about the Umbers, Karstarks, and Manderlys, and reminds Jon and Sansa that the Umbers and Karstarks have already declared for Ramsay. Sansa replies that the Umbers can hang for giving her brother Rickon to Ramsay, but adds the Karstarks declared without knowing they had another choice. She does not specify what she meant by this other "choice" as Davos reminds her of Robb's folly when he executed Rickard.

Harald is present at the Battle of the Bastards as a bannerman to Ramsay, who is ultimately defeated due to the intervention of House Arryn and its bannermen.

Season 7
Harald is reported to have died in the battle against the Boltons, leaving his daughter, Alys Karstark, as the new head of House Karstark. Alys swears fealty to Jon Snow, who pardons House Karstark and allows them to keep Karhold.

Members

 * Lord {Rickard Karstark}, Lord of Karhold. Executed by King Robb Stark under charges of treason for the murder of Martyn and Willem Lannister.
 * {Harrion Karstark}, his eldest son and heir. Killed in battle fighting by the side of King Robb Stark during the War of the Five Kings.
 * {Torrhen Karstark}, his second son. Murdered by Ser Jaime Lannister during an escape attempt.
 * Lord {Harald Karstark}, his youngest son. New Lord of Karhold following the execution of his father by Robb Stark. Participated and subsequently killed in the Battle of the Bastards on the side of House Bolton.
 * Lady Alys Karstark, his daughter. Becomes the Lady of Karhold after Harald's death during the Battle of the Bastards.

In the books
In the A Song of Ice and Fire novels, House Karstark's origins remain the same. The Karstarks are reliable and fierce warriors. They have ties to House Hornwood through the female line. Their military power is formidable, as they are able to field some 300 cavalry and 2,000 infantry. They fought alongside the Starks during Robert's Rebellion.

Lord Rickard has three sons in the books: Harrion, Torrhen, and Eddard, as well as a daughter Alys. Harrion takes part in the Battle of the Green Fork and taken as a hostage (it is unknown if he is still alive), while it is his brothers Torrhen and Eddard are killed by Jaime Lannister during the Battle of the Whispering Wood. Eddard and Torrhen serve as part of Robb Stark's personal bodyguard. When Jaime realizes that his army is lost during the Battle of the Whispering Wood, he makes a final push to single-handedly carve his way through the Northern army in an attempt to kill Robb Stark in single combat. Jaime manages to reach Robb's personal bodyguard and kill several of them, including Eddard and Torrhen, before being knocked unconscious.

Members in the books: There is no Harald Karstark in the books. His character is a condensation of several Karstark members, among them Arnolf, Harrion and Alys.
 * {Rickard Karstark}, executed by Robb Stark for treason
 * His eldest son and heir, Harrion, taken hostage by House Lannister. His fate is unknown.
 * His second son, {Torrhen}, killed by Jaime Lannister in the Battle of the Whispering Wood.
 * His third son, {Eddard}, also killed by Jaime Lannister in the Battle of the Whispering Wood
 * His daughter, Alys. Married to Sigorn son of Styr.
 * Arnolf Karstark, Rickard's uncle, castellan of Karhold. Pretends to be Stannis's ally but collaborates with the Boltons. Imprisoned at Stannis's camp.
 * Cregan, Arnolf's eldest son. Imprisoned at Castle Black.
 * Arthor, Arnolf's second son. Imprisoned at Stannis's camp.
 * Three grandchildren, sons of Arthor. Imprisoned at Stannis's camp.

Because the Karstarks' forces withdrew from the war after King Robb executed Lord Rickard, they are the only major House from the North (besides House Bolton) whose military strength remains relatively intact after the Red Wedding, because their forces were not physically present for the massacre. The Karstark cavalry had been with Robb's field army in the west at Riverrun, and immediately rode back north for Karhold. The Karstark infantry, meanwhile, was in the eastern field army under the command of Roose Bolton. Robb divided his armies by sending the cavalry west and the infantry east. By this point Bolton had decided to betray Robb and seize control of the North, so he intentionally sent the Northern infantry on suicide missions such as the disastrous Battle of Duskendale and Battle of Ruby Ford, in order to bleed the strength of other Northern Houses still loyal to the Starks. Roose ultimately betrayed two thirds of the infantry under his command to their deaths, about 5,000 men. Roose always made sure to send infantry of staunch Stark-loyalists into these ambushes, while holding back and preserving the soldiers of House Bolton. The result was that when Roose reached the Twins for the Red Wedding he had 3,500 men under his command, a mix of his own Bolton forces and Karstark men - Bolton had spared the Karstarks because he judged that their loyalty to the Starks was wavering by this point. Though not entirely clear, the surviving Karstark infantry were apparently not harmed during the massacre at the Red Wedding, though it is clear that none outright joined the Boltons and Freys in attacking the other Stark soldiers. Thus the Karstarks are the only Northern family other than the Boltons to retain their military strength - besides the Northern hill tribes and the crannogmen, whom Robb left behind in the North because they aren't well-armed or used to pitched battles, and would be better suited to harassing any Lannister armies that attempt to invade the North. Even so, due to their continued anger over the execution of Lord Rickard, even after the atrocity of the Red Wedding, the Karstarks become one of the Northern Houses that is more ready to accept the new rule of House Bolton.

It is unclear exactly how much of the Karstark armies survived after the Red Wedding. When Robb initially marched to the south, the Karstarks had 300 cavalry and two thousand infantry. Most if not all of the cavalry survived, and cavalry are worth more than basic infantry levies. Bolton is later said to have an army numbering about 3,000 after the Red Wedding, however, which would imply that only about 500 Karstark infantry survived his intentionally suicidal campaigns in the east - though in all probability, many of the Karstark infantry as well as cavalry may have simply ridden back to the North well before the Red Wedding after Lord Rickard was executed: this would mean that that 500 or so Karstark footsoldiers still in Bolton's eastern army simply hadn't had the opportunity to march back north yet.

Following the battle of Castle Black, Stannis sends letters to all the Northern lords asking for their support, but only Arnolf Karstark - who is not a lord but a castellan - answers the summoning. However, he is actually in league with the Boltons, and encourages Stannis to fight them while intending to switch sides at the critical moment and destroy Stannis's host, as Roose reveals to Ramsay. Arnolf declares publicly that he supports Stannis for another purpose: he hopes that the Lannisters execute Rickard's surviving son Harrion (whose whereabouts and status are unknown) as a payback for Arnolf's "support" of their enemy, and by that - Rickard's daughter Alys will become the heiress of Karhold. Arnolf plans to force her to marry his son Cregan, and after she gives birth to his son - they will gain legal ownership of Karhold, and dispose of Alys.

Arnolf and Hother "Whoresbane" Umber come to Dreadfort. Ramsay introduces them his servant "Reek". Although his physical appearance has changed extremely as a result of the torturing he has been through, they recognize him easily.

Alys learns about her great-uncle's twofold treachery, escapes from Karhold and comes to Castle Black, where she informs Jon Snow about the scheme. Jon sends Tycho Nestoris to find Stannis and warn him of the traitor in his host, and he does. Stannis summons Arnolf to the tower, and once Arnolf arrives and sees Theon - he realizes too late that his treachery is exposed. Arnolf, his son Arthor and three grandsons are disarmed and imprisoned, and Stannis gives them a choice: if they confess - they will be granted quick death, the same manner that Rickard was executed; if they do not - they will be burnt alive.

In the meantime, Alys is wed to Sigorn, Styr's son and successor. Cregan and four of his men hunt for Alys, with a pack of hounds, as if she was an animal. They come to Castle Black, where Jon unceremoniously throws them into ice cells. After several days, Jon informs Cregan about Alys's marriage. Cregan is furious that his father's scheme is foiled, curses Jon and makes idle threats. He warns Jon that killing him will make Jon a kinslayer (similarly to Rickard's statement to Robb), but Jon reminds him that he is not a Stark but a Snow. Jon tells Cregan that Sigorn has enough manpower to take Karhold by force, and gives him a choice: if Cregan yields Karhold - Alys will pardon the women who betrayed her and allow the men to take the black. Cregan answers "Never". Jon advises Cregan that spending more time in the ice cell may change his mind, and if he does not - once Stannis returns, he will execute Cregan, thus his only choice is join the Watch.

The battle between Stannis Baratheon and Roose Bolton has not yet taken place in the novels. Since Stannis lost the battle in the television series, the outcome of the battle in the novels has yet to be seen in The Winds of Winter.