The characters from the medieval fantasy television series Game of Thrones are based on their respective counterparts from author George R. R. Martin's A Song of Ice and Fire series of novels. Set in a fictional universe that has been referred to so far as "The Known World", the series follows a civil war for the Iron Throne of the continent of Westeros, fought between the rival royal and noble families and their respective supporters.

Ned Stark (portrayed by Sean Bean as an adult, Sebastian Croft as a child, and Robert Aramayo as a young adult) is the Hand of the King after Lord Jon Arryn's death. He is known for his sense of honor and justice. He took part in Robert's Rebellion after his sister Lyanna was kidnapped by Crown Prince Rhaegar Targaryen. When Ned's father and brother went south to reclaim her, the "Mad King" Aerys Targaryen burned both of them alive. Ned and Robert Baratheon led the rebellion to unseat him from the throne. As the show opens, Ned has been content to remain in the north, but after the death of Lord Jon Arryn, he is convinced that it is his duty to accept the position of Hand of the King. Ned is not interested in politics, and prefers to rule with honor and follow the law. While investigating the reason for the death of Jon Arryn, he discovers that all three of Robert's children with Queen Cersei were fathered by Cersei's twin brother Jaime. When Ned confronts Cersei about the truth, she has him imprisoned for treason after he publicly denounces Joffrey. Ned is convinced by Varys that if he goes to his death honorably, as he is prepared to do, his daughters will [not] suffer for it. To protect them, he sacrifices his honor and publicly declares that he was plotting to steal the throne and that Joffrey is the true king. Despite Cersei's promise that Ned would be allowed to join the Night's Watch in exile, Joffrey orders Ned's execution for his own amusement and later torments Sansa by forcing her to look at her father's head. His bones are later returned to Catelyn in the Stormlands by Petyr Baelish, who laments Ned's downfall and that he was too honorable to seize power through force, rather insisting the throne pass to Lord Stannis Baratheon, Robert's younger brother. Baelish's preferred course of action, revealed only to Ned, had been to seize Cersei and her children first and rule in Joffrey's name as Regent and Lord Protector. Ned's sacrifice is not in vain, since his notifying Stannis of the truth of Joffrey's parentage sets in motion Stannis' claim to the throne, and ensuring the illegitimacy being made known to all of Westeros. Renly, however, separately lays a claim with the support of mighty House Tyrell. Ned's actions thus set into motion the War of Five Kings against House Lannister and the Iron Throne.

Robert Baratheon (portrayed by Mark Addy) became the King of the Seven Kingdoms after leading a rebellion against Aerys II Targaryen. He was betrothed to Ned Stark's sister Lyanna and loved her deeply, but she was kidnapped by Rhaegar Targaryen. Her father and another brother were killed when they went to King's Landing to reclaim her, which resulted in Robert and Ned Stark's revolt known as Robert's Rebellion, whereupon the Targaryens were all slaughtered or routed from the Kingdoms. Since Robert's family had closer ties to the former Royal family, he was put on the Iron Throne. Now, Robert has grown fat and miserable; he has no more wars to fight, is surrounded by plotters and sycophants, hates and is bored by the constant work needed to manage the Kingdoms properly, and is trapped in a political marriage to the scheming Cersei Lannister, whom he has never loved. He is unaware that none of his three children with Cersei are his, but instead Jaime Lannister's. Under his reign, the realm has been bankrupted and Robert is deeply in debt to his wife's family. Mortally wounded while hunting, he unknowingly leaves no rightful heir behind. His bastards are ordered dead by Joffrey, many of whom are killed, and Gendry is subsequently forced to flee the capital.

Jaime Lannister (portrayed by Nikolaj Coster-Waldau) is a member of the Kingsguard and an exceptionally skilled swordsman. He is Cersei Lannister's twin brother and has carried on an incestuous love affair with her all his life, fathering all three of her living children. He is nicknamed "Kingslayer" for killing the previous King, Aerys II, whom he was sworn to protect. Jaime is captured by Robb Stark's army and held prisoner until he is released by Catelyn Stark and escorted back to King's Landing by Brienne of Tarth. On the road, his sword hand is severed and he reveals that he killed Aerys II to save the population of King's Landing, whom Aerys II was attempting to massacre with wildfire. Upon his return to King's Landing, he retakes his place in the Kingsguard and restarts his affair with Cersei. He travels to Dorne to rescue their daughter Myrcella, but cannot prevent her from being poisoned. After the Faith Militant gain control of the capital, Jaime is relieved of his Kingsguard duties and told to reclaim Riverrun with the Lannister army. Jaime is present at Cersei's crowning following their last child Tommen's suicide, but is later ambushed by Daenerys Targaryen, who has come to Westeros to stake a claim to the Iron Throne. After reuniting with Brienne and joining the effort to defeat the White Walkers, he returns to King's Landing to rescue Cersei from Daenerys' forces. The Lannister siblings die together when Daenerys' dragon, Drogon, destroys the Red Keep.

Catelyn Stark (portrayed by Michelle Fairley) is the wife of Lord Eddard Stark. She is also the elder sister of Lysa Arryn, Lady of the Vale and Mistress of the Eyrie, and Lord Edmure Tully, Lord of Riverrun. Catelyn is the first to suspect that the Lannisters made an attempt on her son Brandon's life and arrests Tyrion Lannister to bring him to the Eyrie for trial. After Tyrion is released and after Eddard is executed, Catelyn joins her son Robb's campaign to rescue Sansa and Arya and defeat the Lannisters. She releases Robb's prisoner, Jaime Lannister, on the condition that he return Sansa and Arya home to Winterfell upon his return to King's Landing. She warns Robb against marrying Talisa Maegyr, which would break a marriage pact he formed with Walder Frey, but is powerless to stop him. Catelyn is killed, along with Robb and Talisa and many Stark loyalists, at the Red Wedding, when Walder Frey - supported by the Boltons and the Lannisters - turns on the Starks for breaking the marriage pact.

Cersei Lannister (portrayed by Lena Headey as an adult and Nell Williams as a child) is the wife of King Robert Baratheon, and queen consort of Westeros. Cersei has a twin brother, Jaime, with whom she has been involved in an incestuous affair from early childhood. All three of Cersei's children are Jaime's. Cersei has a strong desire for power. When she learns that King Robert may be about to discover her affair with Jaime, she arranges for him to be killed and is present when Eddard "Ned" Stark is executed. With her son Joffrey on the throne, she becomes one of his closest advisers and battles with his eventual wife Margaery Tyrell for his affections. When Joffrey is poisoned and her brother Tyrion is framed for the murder, she becomes determined to see Tyrion executed. Tyrion, however, murders their father Tywin and flees King's Landing. With her youngest son Tommen now on the throne and married to Margaery, she seeks the help of the Faith Militant and their leader the High Sparrow to regain control. However, her plans backfires, and she is imprisoned herself by the Sparrows when they learn of her incestuous affairs with Jaime Lannister and Lancel Lannister. After being forced to walk naked through the streets as punishment, she annihilates the Sept of Baelor with wildfire, wiping out the High Sparrow and the Tyrells, and is crowned queen following Tommen's suicide. When Daenerys Targaryen comes to Westeros and challenges her claim, Cersei uses the Great War against the White Walkers as an opportunity to strengthen her forces against Daenerys's depleted armies. She is defeated by Daenerys and her dragon and killed during the destruction of King's Landing.

Daenerys Targaryen (portrayed by Emilia Clarke) is the exiled princess of the Targaryen dynasty. She and her brother Viserys were smuggled to Essos towards the end of Robert's Rebellion. For seventeen years, she has traveled throughout Essos alongside her abusive brother, until they were under the custody of Illyrio Mopatis in Pentos. In exchange for an army, Viserys marries her to the powerful Dothraki warlord Khal Drogo, who gifts her three petrified dragon eggs. When Drogo dies from an infected wound in a fight, Daenerys walks into his burning funeral pyre, birthing three dragons. She later liberates the slaves along Slaver's Bay, ruling over the city of Meereen with her Unsullied army, and eventually defeating the slave masters with her dragons. She then leaves Slaver's Bay for Westeros, in a bid to reclaim her birthright: the Iron Throne. Upon her arrival in Westeros, she meets with Jon Snow, the King in the North, who convinces her to defeat the White Walkers before pressing her claim to the throne. The pair soon fall in love. In Westeros, she loses numerous friends, allies, and two of her dragons in battle, Viserion killed by the Night King and Rhaegal by Cersei Lannister's forces. Overwhelmed by the grave losses she underwent and left with no option but to rule through fear, she uses her last dragon, Drogon, to burn an already surrendered King's Landing and take the Iron Throne by force. She then declares in her speech to her Dothraki and Unsullied that they are not going to end the war, but continue to conquer and liberate the rest of the known world, in the same way she liberated King's Landing. Out of duty, a heartbroken Jon is then forced to kill Daenerys, to prevent the world from meeting the same fate as the city she had reduced to ashes. A grieving Drogon then proceeds to melt the Iron Throne with dragonfire, before taking Daenerys into his claws and flying away from the Red Keep, to the east.

Jorah Mormont (portrayed by Iain Glen) is an exiled knight in the service of Daenerys Targaryen and the son of Jeor Mormont of the Night's Watch. Initially, Jorah is actually spying on the Targaryens for Lord Varys in exchange for a pardon on his crimes. But after learning more about Daenerys, Jorah falls in love with her and decides to protect her and help her regain the Iron Throne. After she is widowed following Khal Drogo's death, he remains with her and becomes the first knight of her Queensguard. Eventually, Jorah's spying is exposed and Daenerys banishes him from her service. He contracts greyscale, a fatal disease, while travelling with Tyrion Lannister. He eventually reunites with his queen, who orders him to cure himself of the greyscale. He journeys to the Citadel where he finds Samwell Tarly, who served under his father Jeor as a brother of the Night's Watch. Samwell is able to cure Jorah, who returns to Daenerys' service and is part of the group who journey beyond the Wall to prove the existence of White Walkers. He dies defending Daenerys at Winterfell during the eventual victory over the Army of the Dead.