Longclaw

"It's my father's sword, and his father before him. The Mormonts have carried it for five centuries. It was meant for my son, Jorah. He brought dishonor to our House... but he had the grace to leave the sword before he fled from Westeros."

- Lord Commander Jeor Mormont

Longclaw is a Valyrian steel sword that remained in the possession of House Mormont for five centuries. When Lord Jeor Mormont retired from his lordship to take the black and command the Night's Watch, he passed it to his son and heir, Ser Jorah Mormont. When Jorah went into exile after trying to sell some poachers into slavery, he left the sword and Ser Jeor Mormont's sister returned it to him on the wall.

Years later, Jeor gave Longclaw to Jon Snow as a reward for saving his life from a wight. Before giving it to Jon he had the pommel remade, replacing the bear with a direwolf, the sigil of House Stark.

Following Jon Snow's coronation as King in the North and the new head of House Stark, Longclaw has become the new Valyrian steel sword of House Stark following the destruction of Ice by Lord Tywin Lannister.

Season 1
Jeor gives the sword to Jon Snow as a reward for saving his life from a wight. Before passing it on to Jon, he remarks that the name "Longclaw" is just as suitable for a wolf as a bear. Mormont has had the pommel remade, replacing the bear with a direwolf, the sigil of House Stark. He mentions that the sword previously belonged to his son, Jorah, who out of shame left Longclaw behind when he fled Westeros. Jon politely tries to refuse, but Mormont insists he keep it.

Jon takes the sword to the dining hall to get the Lord Commander's dinner. He is confronted by the other recruits. Pyp and Grenn are especially vocal in demanding to see the sword.

Season 2
Craster briefly takes Longclaw from Jon after the latter follows him into the woods to see what the man does with his baby sons. Jon is admonished harshly by Mormont for this, who returns the sword to him and instructs him not to lose it again.

Jon later takes Longclaw with him when he takes part in the Great Ranging beyond the Wall led by Mormont. Jon is sent with a scouting party led by Qhorin Halfhand which ambushes a group of wildlings, during which Jon takes the young wildling woman Ygritte captive. Qhorin leaves Jon to execute Ygritte with Longclaw, but Jon cannot bring himself to execute a female captive. She tries to run, resulting in both becoming separated from Qhorin's group, and Jon ends up taking her prisoner.

Ygritte, however, later lures Jon into a trap. He is captured by a group of wildlings led by the Lord of Bones, who take Longclaw from him. Ygritte carries Longclaw as they head back to the main camp of King-Beyond-the-Wall Mance Rayder. As they are about to reach the camp, Ygritte playfully keeps lightly whacking Jon in the head with the flat side of the sword. He eventually dodges and slips behind her, noting that she doesn't know how to wield a sword very well. Qhorin, having also been captured, stages a fight with Jon to convince the wildlings that he is betraying his vows to desert to them, so he can infiltrate Mance Rayder's camp. Qhorin steals a sword from a guard, so Ygritte tosses Longclaw back to Jon so he can defend himself. As Qhorin intended, Jon ends up killing him, impaling him on Longclaw. This marks the first time Jon has ever killed anyone. The wildlings are thus convinced that he wants to defect, and lead Jon into the camp.

Season 3
The Lord of Bones continues to hold onto Longclaw as they lead Jon Snow into the main wildling camp, and he waits outside with it as Jon enters Mance Rayder's tent.

Having gained Mance Rayder's trust, Jon is given back Longclaw. Jon carries Longclaw with him as he climbs back south over the Wall. At Queenscrown, when his true allegiance to the Night's Watch is revealed, Jon fights the wildling company he is with. Jon kills Orell with Longclaw, marking the first time he kills an opponent with the blade (Qhorin's earlier death having been staged).

Season 4
Longclaw is once again used by Jon in combat at the Raid on Craster's Keep. He kills several mutineers with the bastard sword, including Karl.

Jon uses Longclaw during the Battle of Castle Black, killing several wildlings with the bastard sword. In a duel with Styr, the Thenn manages to knock Longclaw out of Jon's hands, but Jon smashes a hammer into his skull and kills Styr. After the battle, Jon intends to find Mance Rayder. Remembering that Jeor told him never to lose the bastard sword again, Jon gives Longclaw to Samwell Tarly for safekeeping.

Season 5
When Janos Slynt refuses to man and repair Greyguard, a ruined castle on the Wall, Jon Snow executes him by beheading him with Longclaw. When the White Walkers attack Hardhome, Jon is able to defeat one in a duel using Longclaw. To the surprise of both Lord Commander and White Walker, the Valyrian Steel sword does not break after coming into contact with the White Walker's ice blade. Pressing his advantage, Jon slashes the Walker with Longclaw; the creature shatters on contact, revealing that dragonglass is not the only thing that can kill a White Walker.

Season 6
After discovering Jon's body in the snow, Davos has Jon's loyalist Black Brothers take the body to a locked room, where he leaves Longclaw nearby. When Davos and Jon's allies are about to face off against Alliser Thorne, Davos grabs Longclaw and prepares to use it against the mutineers. He is prevented from doing so by the timely arrival of wildling reinforcements. Longclaw is then used by Jon Snow to cut the rope which drops Thorne and the mutineers to their death by hanging. A day later, Dolorous Edd is seen giving the sword to Jon as he starts to pack up to leave Castle Black. In the Battle of the Bastards, Jon makes extensive use of Longclaw, felling many foes with it in the melee. After the Bolton army is broken by the arrival of the Knights of the Vale, Jon makes his way inside Winterfell. When Ramsay Bolton makes one last defiant challenge for a one on one duel while choosing a bow and arrow for his weapon, Jon drops Longclaw and picks up a Mormont shield from the ground and blocks three arrows shot by Ramsay until he reaches and beats Ramsay bloody with his bare hands.

The blade officially becomes the new Valyrian steel weapon of House Stark following Jon's ascension as the new head of House Stark and King in the North.