The characters from the medieval fantasy television series House of the Dragon are based on their respective counterparts from author George R. R. Martin's 2013 novella The Princess and the Queen, his 2014 novella The Rogue Prince and his 2018 novel Fire & Blood. The series follows the devastating war of succession for the Iron Throne of the continent of Westeros known as the "Dance of the Dragons", fought between Queen Rhaenyra Targaryen (the Blacks) and King Aegon II Targaryen (the Greens) and their respective supporters.

Viserys I Targaryen (portrayed by Paddy Considine), known posthumously as "Viserys the Peaceful", is the fifth King of the Seven Kingdoms. He is the grandson of the previous King Jaehaerys the Conciliator and the husband of Queen Aemma Arryn and later Queen Alicent Hightower. He is the father of Queen Rhaenyra Targaryen and the short-lived Prince Baelon Targaryen through his first wife Aemma and King Aegon II, Queen Helaena, Prince Aemond, and Prince Daeron Targaryen through his second wife Alicent. He was a dragonrider who was bonded to the dragon Balerion until he died of old age. He was among the candidates to succeed his grandfather as ruler of the Seven Kingdoms and during the Great Council at Harrenhal he was chosen as heir over his older cousin Princess Rhaenys Targaryen, despite her better claim to the Iron Throne. Nine years later, he held the Heir's Tournament to celebrate the birth of his son Baelon but due to a difficult pregnancy, Viserys decided to sacrifice his wife Aemma by ordering Grand Maester Mellos to perform a C-section on her to ensure that Viserys gets a male heir, causing Aemma's death while Baelon dies anyway hours later. He then makes his only surviving child Rhaenyra his heir, a position previously held by his younger brother Prince Daemon Targaryen, and informs her of King Aegon the Conqueror's dream regarding the "Prince That Was Promised". He also cuts his finger on the Iron Throne, which while seemingly innocent at first, would develop into a far worse infection over time. Still seeking a male heir, Viserys goes against the Small Council's advice to marry Lady Laena Velaryon, the young daughter of Lord Corlys Velaryon, and soon marries Alicent who gives him a son, but Viserys decides to keep Rhaenyra as his heir anyway. He organizes a royal hunt on Aegon's second nameday while actively ignoring the ongoing War for the Stepstones and seeks to make a powerful alliance by marrying off Rhaenyra so she can have children to secure his bloodline further. To maintain ties with the wealthy House Velaryon, he and Corlys arrange a marriage between Corlys' son Ser Laenor Velaryon, and Rhaenyra, repairing the rift between the Velaryons and House Targaryen. Ten years later, the cut that Viserys received from the Iron Throne began to take its toll, and Viserys became increasingly weak as the years passed and began suffering from a form of leprosy. To continue fulfilling his role as king, he began taking the powerful opiate milk of the poppy while opposing political factions formed under Rhaenyra and Alicent that Viserys was unable to stop spiraling out of control. Six years later, as his body deteriorated and he struggled to walk, the Hand of the King Ser Otto Hightower now fulfilled most of Viserys' royal duties. Viserys holds a final family gathering, bringing his children and closest allies together in an attempt to stop any further conflict between them. While it was seemingly a success, he soon became delirious and bedridden and with his dying words he mistakes Alicent for Rhaenyra and rambles on about the "Prince That Was Promised", but Alicent mistakenly believes that he was telling her that he wanted their son Aegon on the throne. Viserys soon dies from his illness, and the Small Council enacts a long-held plan to make Aegon the new king, despite Rhaenyra still being the chosen heir, reigniting the feud between Rhaenyra and Alicent's factions that eventually escalates into civil war.

In season 2, he appears during Daemon's mysterious visions while staying in Harrenhal.

Daemon Targaryen (portrayed by Matt Smith), also known as the "Rogue Prince" for his unpredictable behavior, is the younger brother of King Viserys I Targaryen and the husband of Lady Rhea Royce, Lady Laena Velaryon and later his niece Queen Rhaenyra Targaryen. He is the father of Lady Baela Targaryen and Lady Rhaena Targaryen through his second wife Laena and Prince Aegon "the Younger", Prince Viserys, and the stillborn Princess Visenya Targaryen through his third wife Rhaenyra. He is a dragonrider who is bonded to the dragon Caraxes and wields the Valyrian steel sword "Dark Sister". While he was the heir to the Iron Throne, he was considered unfit to rule by the Small Council due to his reluctance to be involved with politics and his brutal methods of dispensing justice as the Lord Commander of the City Watch. Following the death of Queen Aemma Arryn and her infant son Prince Baelon Targaryen, Viserys disinherits Daemon after he mockingly referred to the deceased Baelon as the "heir for a day". Viserys then names his daughter Rhaenyra as the new heir so Daemon and his lover Mysaria leave King's Landing and occupy Dragonstone. Daemon later steals the deceased Baelon's dragon egg simply to get his brother's attention by lying about it being for an unborn child of Mysaria, resulting in Rhaenyra retrieving the egg peacefully and Mysaria leaving Daemon after realizing he was just using her. After Viserys refuses to confront the threat of the Triarchy, Lord Corlys Velaryon requests Daemon's help in the War for the Stepstones. After a three-year campaign, Daemon kills the leader of the Triarchy Craghas Drahar during the climactic Siege of Bloodstone, winning the war, and is bestowed the title of "King of the Narrow Sea". Daemon soon returns to King's Landing and kneels before Viserys and abdicates his crown, claiming Viserys as the one true king. After discovering that Rhaenyra needs a husband, Daemon takes her into the streets of King's Landing at night where he seduces her but is unable to consummate their affair. When Viserys is informed of Daemon's exploits, believing that his brother still sought the Iron Throne, he orders Daemon to return to his estranged wife Rhea. Daemon then travels to the Vale and murders his wife so that he can marry Rhaenyra. However, Rhaenyra is soon married to Ser Laenor Velaryon as part of a political alliance with Corlys, but Daemon manages to get the attention of and later marries Laena. Ten years later, Daemon, Laena, and their daughters live in Pentos until Laena suffers from prolonged labor during her third pregnancy and commits suicide. Daemon attends her funeral at Driftmark where he reunites with Rhaenyra who proposes marriage to strengthen her claim to the Iron Throne but cannot marry with Laenor still alive. Daemon then conspires with Laenor's lover Ser Qarl Correy to fake Laenor's death so he and Qarl can run away together, allowing Daemon and Rhaenyra to get married. Six years later, he attends Ser Vaemond Velaryon's petition to the Iron Throne to name him the heir to Driftmark. After Vaemond publicly insults Rhaenyra and declares that her children are illegitimate, Daemon decapitates him in response. Following the death of Viserys and King Aegon II Targaryen usurping the throne, Rhaenyra gives birth to the stillborn Princess Visenya Targaryen, and at the funeral, Daemon crowns Rhaenyra as the rightful Queen of the Seven Kingdoms.

In season 2, with the death of Prince Lucerys Velaryon, Daemon becomes frustrated with the inaction of Rhaenyra and her supporters. After he promises an imprisoned Mysaria her freedom in exchange for one of her agents, he hires the City Watch guard Blood and Mysaria's contact, the ratcatcher Cheese, to assassinate Prince Aemond Targaryen but Prince Jaehaerys Targaryen is murdered and decapitated instead. Rhaenyra suspects Daemon of being responsible before stating that she cannot trusts him, leading to Daemon departing Dragonstone. Daemon flies to Harrenhal and singlehandly takes the castle for Rhaenyra's cause after Ser Simon Strong willingly yields to him. Daemon later experiences a vision of a young Rhaenyra sewing Jaehaerys' head back onto his body. When he awakens, Daemon finds himself at Harrenhal's godswood where Alys Rivers tells Daemon that he will die there. He continues to have visions induced by Alys during his time at Harrenhal regarding his feelings of guilt surrounding Rhaenyra, Laena, Viserys, and his mother Princess Alyssa Targaryen. He summons House Tully and House Blackwood to meet him at Harrenhal and discusses terms with Ser Oscar Tully and later Ser Willem Blackwood. Alongside Willem, Daemon confronts Lord Amos Bracken who refuses to surrender, despite Daemon's threats that he will burn him alive with Caraxes. He then urges Willem to use terror tactics on the smallfolk living on the Bracken's lands. Daemon later begins the reconstruction of Harrenhal to garrison his growing army and is later informed that House Bracken has surrendered to House Blackwood but several Riverlords soon confront Daemon over the brutality of the Blackwood's pillaging and raiding and refuse to pledge their houses to him. After Daemon awakens from another vision, he threatens Simon with a knife and questions his loyalty before deciding that he should go confront the Riverlords himself. Alys stops him from departing, and Daemon asks for her counsel. She convinces him that he should wait for three days which he reluctantly agrees to. Three days later, Simon informs Daemon that Alys had attempted to aid the sick Lord Grover Tully, who died shortly afterward. Daemon soon holds a gathering of Riverlords at Harrenhal where Oscar, now the Lord Paramount of the Riverlands, agrees to uphold his grandfather's oath and support Queen Rhaenyra Targaryen's claim to the Iron Throne. Oscar then demands that Willem be punished for his transgressions against House Bracken under Daemon's orders so that the other Riverlords can begin to trust him. Daemon obliges and beheads Willem so that he may finally form his army of Rivermen. After Ser Alfred Broome arrives in Harrenhal, he privately meets with Daemon in Harrenhal's godswood and tries to persuade him to claim the throne for himself. Alys later brings Daemon to the godswood, claiming that he is now ready to experience a final vision, this time of the future. Daemon experiences a multitude of visions including the Targaryen bastard Ser Brynden Rivers becoming the Three-Eyed Raven, a White Walker marching with an army of wights, Daemon and Caraxes' deaths in battle, the birth of Daenerys Targaryen's dragons, and Rhaenyra sitting on the Iron Throne. Daemon is then encouraged by a vision of Queen Helaena Targaryen that he has a part to play in deciding the future. After Rhaenyra arrives at Harrenhal, having been informed of Daemon's potential betrayal by Simon, Daemon pledges himself and his army of rivermen to Rhaenyra and her claim to the throne, stating that he will remain by her side.

Rhaenyra Targaryen (portrayed by Emma D'Arcy as an adult and by Milly Alcock as a teenager) is the disputed Queen of the Seven Kingdoms. She is the daughter of King Viserys I Targaryen and Queen Aemma Arryn, and the wife of Ser Laenor Velaryon and later her uncle Prince Daemon Targaryen. She is the mother of Prince Jacaerys, Prince Lucerys, and Prince Joffrey Velaryon through her lover Ser Harwin Strong and Prince Aegon "the Younger", Prince Viserys, and the stillborn Princess Visenya Targaryen through her second husband Daemon. She is a dragonrider who is bonded to the dragon Syrax. She is also the childhood friend of Lady Alicent Hightower, with them having grown up together in the Red Keep. Following the death of Aemma and Rhaenyra's infant brother Prince Baelon Targaryen, Rhaenyra is made heir to the Iron Throne and Viserys informs her of King Aegon the Conqueror's dream regarding the "Prince That Was Promised". Rhaenyra personally selects Ser Criston Cole to join her father's Kingsguard and he becomes her royal protector. She also retrieves the deceased Baelon's dragon egg that was stolen by Daemon, who sought his brother's attention after he lost his inheritance to Rhaenyra. She is distraught after learning of her father's marriage to Alicent and grows concerned after she gives Viserys a son, Prince Aegon Targaryen. After Daemon is victorious during the War for the Stepstones, he takes Rhaenyra into the streets of King's Landing at night where he seduces her but is unable to consummate their affair. A frustrated Rhaenyra later seduces Criston instead despite his reluctance and the fact that the Kingsguard are sworn not to sleep with anyone. When Alicent confronts her about the affair with Daemon, she denies it, but Criston later confesses which makes Alicent feel betrayed. After failing to find a husband so Viserys can have grandchildren to secure his bloodline, Rhaenyra agrees to marry Laenor as part of a political alliance with House Velaryon. Rhaenyra and Laenor come to an understanding that they will perform their royal duties together but that Laenor can continue his relationship with his male lover, Ser Joffrey Lonmouth, and Rhaenyra can continue her affair with Criston. However, Rhaenyra breaks off her affair with Criston who then kills Joffrey during their royal wedding feast. Ten years later, Rhaenyra's first three sons had all been fathered by her lover Ser Harwin Strong, with Laenor being their father legally so they remain legitimate. Rhaenyra attends the funeral of Lady Laena Velaryon at Driftmark but following an altercation that results in Lucerys partially blinding Alicent's son Prince Aemond Targaryen, Alicent attempts to have Lucerys' eye gouged out in return, and when refused, she wounds Rhaenyra. Rhaenyra reunites with Daemon and proposes marriage to strengthen her claim to the Iron Throne and Daemon helps fake Laenor's death which allows him to go into exile in Essos and Daemon and Rhaenyra soon get married. Following the death of Viserys and Aegon usurping the throne, Rhaenyra gives birth to the stillborn Princess Visenya Targaryen, and at the funeral, Ser Erryk Cargyll arrives with Viserys' crown which Daemon uses to crown Rhaenyra as the rightful Queen of the Seven Kingdoms. She sends her sons Jacaerys and Lucerys as envoys to ensure that House Stark, House Arryn, and House Baratheon keep their oaths to support Rhaenyra's claim to the Iron Throne, but Lucerys is soon killed by Aemond and his dragon Vhagar.

In season 2, Rhaenyra discovers the partial remains of her son's dragon Arrax but nothing remained of Lucerys as he was devoured whole. She then holds a funeral for him at Dragonstone. Following the murder of Prince Jaehaerys Targaryen, Rhaenyra worries that her popularity will suffer and cannot trusts Daemon after he is revealed as responsible. In retaliation for Jaehaerys' murder, Criston sends Ser Arryk Cargyll to assassinate Rhaenyra but she is saved by Erryk although the confrontation results in both of the brother's deaths. After Lady Baela Targaryen informs the Black Council of Criston leading an army into the Crownlands, Rhaenyra, with assistance from Mysaria and Ser Steffon Darklyn, infiltrates King's Landing disguised as a septa and visits Alicent at the Grand Sept in an attempt to make peace. Rhaenyra learns that Alicent had misinterpreted Viserys' final words regarding the "Prince That Was Promised" which led to her wanting to put Aegon on the throne. Alicent dismisses Rhaenyra's pleas and warns her that the war is inevitable. After returning to Dragonstone she sends Princess Rhaenys Targaryen to Rook's Rest as Criston's army prepares to lay siege. As her heir, she also informs Jacaerys of the Aegon the Conqueror's dream regarding the "Prince That Was Promised". Following the Battle at Rook's Rest, resulting in the death of Princess Rhaenys Targaryen, Rhaenyra sends Baela to offer Corlys the position of Hand of the Queen, sends Ser Alfred Broome to meet with Daemon at Harrenhal, and when conversing with Jacaerys, talks of finding dragonriders for Vermithor and Silverwing, to match the strength of Vhagar. After Jacaerys discovers that Steffon had a distant Targaryen ancestor, Rhaenyra requests that he attempt to bond with an unclaimed dragon. Steffon willingly agrees, and Rhaenyra witnesses him unsuccessfully try to claim the dragon Seasmoke and be burned alive. After Lord Bartimos Celtigar questions Rhaenyra's decision-making, he strikes him in front of the castle servants and guards. Mysaria reports to Rhaenyra that her spies had begun inciting harmful rumors in King's Landing to undermine Aegon's rule, including that the upper class are living in luxury while the smallfolk starve. Mysaria later reports her success after she sends Targaryen-bannered boats filled with food to King's Landing which incites a riot as thousands of smallfolk fight for the food and openly praise Rhaenyra for feeding them. Mysaria then reassures Rhaenyra after she has doubts about winning the war and expresses that she remains loyal to Rhaenyra as she is treated as an equal. Rhaenyra then comforts Mysaria and they passionately kiss until they are interrupted by Ser Lorent Marbrand who brings news that the dragon Seasmoke has been claimed by an unknown rider, and Rhaenyra heads out on Syrax to confront them. After confronting Addam of Hull and accepting him as an ally, she is encouraged that anyone with Valyrian blood has a chance to claim a dragon. Despite the objections of Jacaerys, Bartimos, and the dragonkeepers, Rhaenyra requests that Mysaria send word throughout King's Landing that she is seeking Targaryen bastards in an attempt to find new dragonriders. During the Red Sowing, Rhaenyra summons the dragon Vermithor before the dragonseeds and watches as dozens of them are killed by Vermithor until he is eventually claimed by Hugh Hammer. After later discovering that Ulf White managed to claim the dragon Silverwing, she and her new dragonriders confront Aemond when he chases Silverwing back to Dragonstone on Vhagar, forcing him to retreat after witnessing the three adult dragons. She holds a feast for her new dragonriders and promises them knighthoods if they win the war and states her plan to send them to attack the opposing cities of Oldtown and Lannisport. After Maester Gerardys brings her a message from Ser Simon Strong regarding Daemon's potential betrayal, she heads to Harrenhal with Addam. She confronts Daemon and he pledges himself and his army of rivermen to Rhaenyra and her claim to the throne, stating that he will remain by her side. After returning to Dragonstone, Mysaria comforts Rhaenyra after she debates sending her dragons to war despite the countless deaths it would lead to, but Mysaria assures her that her cause is just. She is later confronted by Alicent at night who admits her faults and wishes to leave King's Landing open for capture so Rhaenyra can end the war quickly. Rhaenyra is dissatisfied with allowing Aegon to live, as his claim to the throne is what started the conflict, and she forces Alicent to choose between peace or escalating the war. Alicent reluctantly agrees with her terms and Rhaenyra allows her to leave Dragonstone.

Otto Hightower (portrayed by Rhys Ifans) is the father of Ser Gwayne Hightower and Queen Alicent Hightower who served as the Hand of the King on the Small Council under King Jaehaerys the Conciliator, King Viserys I Targaryen and King Aegon II Targaryen. Following the death of Queen Aemma Arryn, he makes Alicent get close to the grieving king, which later results in their marriage and the birth of Otto's eldest grandchild Aegon. Otto is pressured by his older brother Lord Hobert Hightower to help make Aegon the heir to the Iron Throne over the chosen heir Princess Rhaenyra Targaryen as it would strengthen their house's power. He is later dismissed as Hand of the King by Viserys after he discovers that Otto set Alicent up to become his wife and believes Otto's judgment to be compromised. Ten years later, he is reinstated as Hand of the King following the sudden death of Lord Lyonel Strong, orchestrated by Larys Strong to help Alicent who wanted her father to regain his position. Otto then spent several years conspiring with fellow Small Council members Ser Tyland Lannister, Lord Jasper Wylde, and Grand Maester Orwyle to eventually usurp the throne and make Aegon king while Viserys was slowly succumbing to his crippling illness. Following Viserys' death, he finally enacts their plan and Aegon is quickly crowned king.