Jeor Mormont was the 997th Lord Commander of the Night’s Watch. Before joining the Night’s Watch, he was the head of House Mormont and the Lord of Bear Island.
Jeor’s son Jorah originally inherited his father’s titles, but disgraced himself by selling slaves and fled to the Free Cities. As a result, Jeor’s sister Maege took on the family’s titles. Years later, Jeor takes Jon Snow, a recent addition to the Night’s Watch, as his personal steward, grooming him for command. He also comes to see Jon as a surrogate son, and gives him Long claw, his house’s ancestral weapon.
Wishing to investigate rumours of Free Folk amassing and White Walkers being sighted, Mormont led a great expedition beyond the Wall; however, he was killed during the Mutiny at Craster’s Keep, when some of his own men rebelled against him for not standing up to Craster.
Jeor Mormont, nicknamed The Old Bear, is the Lord Commander of the Night’s Watch and leads from his headquarters at the fortress of Castle Black. Jeor was once the Lord of Bear Island and head of House Mormont until he abdicated his seat in favour of his son, Ser Jorah Mormont, and joined the Night’s Watch. He quickly rose through the ranks to become Lord Commander. Jorah disgraced himself by capturing poachers on the island and selling them into slavery, and then fled to the Free Cities to avoid reprisal for his crimes, leaving Jeor’s sister Maege to rule Bear Island.
Lord Commander Mormont watches the new trainees practicing and talks to Tyrion Lannister about their lack of resources, which are made all the worse with the prospect of the coming winter. He and Maester Aemon later request that Tyrion bring word of their problems to Tyion’s sister Queen Cersei Lannister and ask for their help.
Jeor conducts a ceremony to induct the new class of recruits into the Night’s Watch, reminding them of the honour of their brotherhood. Jeor chooses Jon Snow, the illegitimate son of Lord Eddard Stark, as his personal steward. When their assignments are handed out, Jon is initially disappointed because he had always wanted to be a ranger like his uncle Benjen Stark but Samwell Tarly suggests that the Lord Commander wants to groom Jon for command.
Jeor is summoned when the bodies of Othor and Jafer Flowers are discovered north of the wall and returned to Castle Black. Sam notices that they haven’t rotted, to which Jeor comments that even though Sam is a coward, he is not stupid. Later Jeor receives word via raven that Eddard has been declared a traitor and arrested. He calls for Jon and informs him of this the news about his family. Jeor is understanding of Jon’s feelings of distress for his father and sisters, assuring Jon of his sisters’ safety, but reminds him of his duty. Later, Jon attempts to stab Ser Alliser Thorne after he mocks his family for being traitors. Jeor witnesses this and confines Jon to quarters. That night Jeor enters his own quarters to find Jon fighting a Wight, Othor risen again. Jon stabs the Wight but it rises and pulls Jon’s sword out of its abdomen. Jon throws Jeor’s lantern on it, lighting it on fire.
Thanking Jon for his action, and growing to see Jon as a surrogate son, Mormont gives him a Valyrian steel sword, Long claw, an heirloom of House Mormont. Jeor had previously given to his son and heir, Ser Jorah Mormont, but Jorah had left the sword behind when he went into exile leaving Westeros in disgrace.
Jon attempts to leave Castle Black and join his brother Robb’s army after he learns of Eddard’s execution, but is persuaded to stay by his friends. Jeor is aware of Jon’s attempted desertion but refuses to punish him, saying it is more important that he came back. Jeor tells Jon that the true danger and threat to the Seven Kingdoms comes from the White Walkers and wights beyond the Wall, not the looming civil war, and asks for Jon’s help. Mormont aims to lead the Night’s Watch in force beyond the Wall, find the missing Benjen Stark and identify and eliminate the threat posed by the White Walkers. Jon joins Mormont’s party as it leaves Castle Black.
In the far North the great ranging of the Night’s Watch traverses the Haunted Forest. They have passed six abandoned wildling villages and have been traveling for months. They reach Craster’s Keep, the home of Craster, an unsavoury ally who marries his daughters and has no sons. Jeor questions Craster and learns that he has not seen missing First Ranger Benjen Stark in years. Craster tells him that the wildling’s are assembling under King-Beyond-the-Wall Mance Rayder. After Jon provokes Craster, Jeor aggressively reprimands him outside and confirms that he is indeed grooming him for command: he tells Jon, “You want to lead one day? Well learn how to follow.”
The Watch is forced to move on when Jon follows Craster into the woods and sees him leaving a son for the White Walkers. Craster catches him and beats him. Jeor reveals to Jon that he has always known that Craster sacrificed his sons to Wildling gods but ignored it because of his value as an ally. The ranging next camps at the Fist of the First Men where they await Qhorin Halfhand and his party from The Shadow Tower. Qhorin arrives and reports sighting lookouts in the Skirling Pass. Given Mance’s background as a deserter from the Watch, Qhorin predicts that the wildling’s will be more organised. He suggests they accordingly shift to wildling tactics and use a small group of scouts to overcome the lookouts. Jon requests to be part of the mission and Jeor accepts with encouragement from Qhorin and a promise from Samwell Tarly that he will take on Jon’s duties as a steward.
As wights and their masters descend on the Fist of the First Men, the Night’s Watch are forced to try and pull back to the Wall to warn the remaining garrison of the impending attack. During the retreat Mormont saves Samwell Tarly from a wight, only to learn that he had failed to dispatch ravens requesting aid as ordered, leaving the Night’s Watch to fend for itself. Mormont angrily berates Tarly for bungling his one and only task.
Mormont leads the ragged survivors of the Night’s Watch expedition to Craster’s Keep. Craster mocks the survivors of the Battle of the Fist of the First Men when they reach his Keep. He initially wants to refuse them shelter until he notices some of them stroking their weapons. Fearful that in desperation they might try to rush him, he relents. As the black brothers warm by his hearth, Craster mocks them. Craster insists that the black brothers should be grateful for his generosity and that he is a “godly man” for helping them. Mormont tensely questions that he is a godly man, but Craster insists that he is – to the “real gods”, the White Walkers, who consume entire armies on their way to the Wall but will spare Craster for his loyalty. Some of the wounded men die from their injuries, and Mormont is shown giving the traditional Night’s Watch eulogy as the corpse of a ranger named Bannen is burned on a pyre.
In the main hall, Mormont is checking a map in his journal, as Craster continues to crassly berate the men of the Night’s Watch. Mormont says that they have to stay long enough for their wounded to recover enough to be fit to travel, but Craster waves this off, saying they’ve recovered as much as they ever will. Craster openly suggests that they should just kill the men who are so severely wounded that they won’t be able to travel, and if Mormont is reluctant to do the deed himself, he can just leave and Craster will finish them off. Mormont declines. Another young Night’s Watchman, Karl, comes in to complain that Craster is feeding them nothing but bread cut with sawdust, and he wants to know where Craster keeps his hidden larder. Meanwhile, Craster is sitting there getting quite drunk on the wine they gifted to him when they first came. Rast joins in the accusations, and Craster admits that he has winter stockpiles, but he needs those to feed his women and refuses to share them. Rast calls Craster a bastard – at which Craster becomes enraged and threatens Rast with an axe. Mormont restraints Rast, and Craster shouts that he’s throwing them all out to lay down outside in the cold on their empty bellies. Craster says he will chop the hands off the next man who calls him “bastard”. A tense moment of silence passes, and Mormont grabs Rast to lead him out the doorway…
…when Karl, firmly staring directly at Craster, challenges him by calling him a “daughter-fucking, wildling bastard”. Craster lunges forward at Karl in a blind rage, but he is drunk and clumsy. Without flinching, Karl holds off Craster’s axe with his left hand, while using his right hand to ram a dagger through Craster’s throat, which goes up into the roof of his mouth. He flings the dying Craster to the ground, then punches one of Craster’s wives who is present, demanding to know where the hidden food is kept. Lord Commander Mormont bellows that the gods will curse him for this, as a guest killing a host who has formally accepted him into his home breaks all the laws of gods and men.
Karl shouts that there are no laws beyond the Wall. Karl continues to threaten the girl with a knife, so Mormont draws his sword, which makes Karl drop the girl and begin to face off against Mormont with his dagger. As Mormont threatens to have Karl executed, Rast comes up behind Mormont and literally stabs the Lord Commander in the back, which makes Mormont drop his sword. For a brief moment the men stare in shock, then Grenn charges and tackles Karl. The entire room explodes into pure bedlam.
The desperate Night’s Watch recruits like Rast, mostly conscripted criminals exiled to the Wall, turn on officers who are loyal to Mormont, as well as some of the other common recruits like Grenn who stay loyal. Quick flashes of the fight go by as no one can really perceive what’s happening, and the mutiny spreads throughout Craster’s Keep. In the midst of it, Mormont turns around to fight off Rast. Mormont may have a knife in his back but he is twice Rast’s size and completely enraged. Mormont grabs Rast by the throat and lifts him off his feet, one-handed, then spins him around and hurls him against the opposite wall. Still choking Rast, Mormont nearly succeeds in crushing Rast’s windpipe with his bare hand – but then Mormont starts to cough up thick red blood. His knife wound is mortal. The injured Mormont then sinks to the ground and continues to cough up blood. Now that Mormont is on the ground unarmed and helpless, Rast grabs a knife and repeatedly pounds it into Mormont’s throat until the Old Bear is dead.
Samwell Tarly later informs Maester Aemon of Mormont’s murder, and Aemon orders him to send letters all over Westeros reporting it and pleading for help. Davos Seaworth shows the letter to Stannis Baratheon, who under Melisandre’s advice, decides to travel to the Wall to aid the Night’s Watch against any threats towards the Seven Kingdoms.
After the Mutiny at Craster’s Keep, Karl and the mutineers desecrated Mormont’s corpse. Karl has taken the late Lord Commander’s skull as a crude cup from which to drink wine and use for his amusement.
Jon later references Mormont’s murder as a reason for several of his black brothers to aid him in going to Craster’s Keep and killing the mutineers in order to stop them from revealing vital information to Mance Rayder. Mormont is avenged when Karl and Rast are killed by Jon and Ghost, respectively, during the raid on Craster’s Keep.
Jeor’s hope for Jon to succeed him is realised when Jon is elected the new Lord Commander of the Night’s Watch.
While traveling to Meereen, Tyrion Lannister tells Jorah Mormont that he met his father Jeor during his trip to the Wall, and reveals that he was killed by his own men during a ranging beyond the Wall. Jorah is visibly shocked to hear of his father’s murder.
During a visit to Bear Island, Jon invokes Jeor’s name as he attempts to enlist his niece, Lyanna Mormont, into joining his campaign to take back Winterfell back from Ramsay Bolton.
While training to become a maester in the Citadel in Old town, Samwell Tarly attempts to cure Jorah Mormont of his greyscale infection, citing his respect for Jeor as a primary reason, and revealing that he was with Jeor when he died.
When Jorah is deemed fully cured of the disease, by Archmaester Ebrose, Sam says it was the least he could do due to his relationship with Jeor.
Jon makes himself known to Jorah on his arrival on Dragon stone, mentioned his stewardship under the command over Jeor.
When Tormund meets Jorah and learns he is Jeor’s son, Tormund threatens him because Jeor had killed many of Tormund’s people, until Jon convinces Tormund to let it go.
During their trip beyond the Wall, Jorah and Jon talk about their fathers, Jeor Mormont and Ned Stark. They discuss how both were honourable men who met unjust ends. Jon offers Jorah back the sword Long claw, claiming that it belongs to the Mormont family. After a brief moment, however, Jorah gives the sword back to Jon, claiming that Jeor gave it to him and that Long claw now belongs to Jon – and his children afterward.