Kinslaying is a great taboo in Westeros. Any individual who kills a member of their own family is dubbed a kinslayer, and believed to be cursed forever. Many nobles and smallfolk believe this, and thus those who slay their own blood are usually looked down upon or shunned. Across Westeros, in the religions of the old gods, the Faith of the Seven, and even of the Drowned God, men state that "no man is so accursed as the kinslayer" and that "the kinslayer is accursed in the eyes of gods and men".
The stigma and notoriety of kinslaying can go both ways. For example, Victarion Greyjoy hates his brother Euron and thinks about killing him, but the stigma and curse associated with kinslaying is what restrains him from doing so. However, when Tristifer Botley, who believes Aeron Greyjoy was killed by his brother Euron, says Euron is afraid of being seen as a kinslayer, Asha Greyjoy responds that if Euron heard this, he would murder one of his sons to prove them wrong.
According to George R.R. Martin:
There are degrees in kinslaying, as in anything else. Fighting a battle in which a brother dies might be frowned upon, but killing him with your own hand would be considered far worse.
Kinslayers and people suspected of kinslaying
- Stannis Baratheon: conceived a shadow assassin with Melisandre that went on to slay his younger brother King Renly Baratheon. Note, Renly intended that Stannis would die in battle (by his hand or by one of his men's), and it is unclear if Stannis pre-approved of Melisandre's sorcery.
- Tyrion Lannister: accused of the murder of his nephew, King Joffrey I Baratheon, of which he is actually innocent. Also held responsible for the murder of his own father, Tywin Lannister, of which he is actually guilty.
- Ramsay Snow: his own father, Lord Roose Bolton, suspects he poisoned his half-brother Domeric, Roose's trueborn son.
- Euron Greyjoy: is suspected of being involved in the death of his older brother Balon. Because of the disappearence of his younger brother Aeron after the Kingsmoot, some ironborn think that he murdered him as well. Euron confesses to Aeron, whom he had seized and captured, that he killed Balon, though his was not the hand that did so, and two of his half-brothers, Harlon and Robin.
- Robb Stark: when preparing to execute Rickard Karstark, per Eddard Stark's custom that the man who passes the sentence should also swing the sword, Karstark calls Robb a kinslayer due to the blood ties between House Stark and House Karstark. However, Rickard was stretching the concept of kinslaying in hopes of saving his head, as House Karstark split from House Stark over a thousand years before, and Robb was only a distant cousin through his great-great-great grandmother Alys Karstark.
- Theon Greyjoy: named a kinslayer by some for his supposed murder of Bran and Rickon Stark; although they are not his blood kin, he was their father's ward and was raised with them.
- Gilwood Hunter: Was accused by his two younger brothers Eustace and Harlan of killing their father Eon Hunter.
Historical kinslayers and people suspected of kinslaying
- The Bloodstone Emperor killed his own sister.
- Harwyn Hoare: He was suspected of murdering his middle brother Harlan Hoare, who died from falling of a horse shortly before their father died.
- Erich Durrandon: Known as Erich Kin-Killer when he slew his brother King Durran, who was possibly Durran the Young.
- Jonos Arryn: was called Jonos the Kinslayer when he killed his own brother, Ronnel, and their family during the reign of Aenys.
- Queen Visenya Targaryen: She was suspected of poisoning her nephew and stepson Aenys so her son Maegor could succeed.
- King Maegor I the Cruel: For slaying his nephew Aegon Targaryen and later having another nephew Viserys Targaryen tortured to death.
- Lord Stark (grandson of Brandon the Daughterless): For slaying Bael the Bard, the King-Beyond-the-Wall, ignorant that Bael was his actual father.
- Lord Larys Strong: Is suspected of beginning the fire at Harrenhal in which his father, Lord Lyonel Strong, and elder brother Ser Harwin Strong, died.
- King Aegon II: For feeding his half-sister Rhaenyra Targaryen to his dragon Sunfyre during the Dance of the Dragons.
- Aemond Targaryen: For killing his nephew Lucerys Velaryon during the Dance of the Dragons.
- Daemon Targaryen: For killing his nephew Aemond Targaryen during the Dance of the Dragons, and sending the assassins who murdered his great-nephew Jaehaerys Targaryen.
- Ser Erryk Cargyll: For slaying his twin brother Ser Arryk Cargyll during the Dance of the Dragons; each died by the other's sword.
- Ser Arryk Cargyll: For slaying his twin brother Ser Erryk Cargyll during the Dance of the Dragons; each died by the other's sword.
- King Viserys II: Was alleged to have poisoned his nephew Baelor I Targaryen, though many people think Baelor fasted himself to death.
- King Aegon IV the Unworthy: Was alleged to have poisoned his father Viserys II.
- King Maekar I: Was called a kinslayer when he accidentally slew his own brother Baelor "Breakspear" Targaryen in a trial of seven.
- Brynden Rivers: Was called a kinslayer when he killed his half-brother Daemon Blackfyre and Daemon's sons Aegon Blackfyre and Aemon Blackfyre during the Battle of the Redgrass Field. Later Brynden executed another of Daemon's sons, Aenys Blackfyre.
- Maelys Blackfyre: Was called a kinslayer because he supposedly consumed his own twin in the womb. Later in life he killed his own cousin, Daemon.
- Gerold Lannister: He was suspected of murdering his older brother Tybolt Lannister and Tybolt's daughter Cerelle Lannister.
Fratricide ... my lord, this is evil, unthinkable.
– Maester Cressen, considers the thought of Stannis killing his younger brother, Renly
– Jaime Lannister's thoughts
The gods hate kinslayers, even when they kill unknowing.
Kinslaying is dry work. It gives a man a thirst.
The gods hate kinslayers.
- Customs, for additional information on customs and traditions of Westeros.
- A Clash of Kings, Chapter 44, Tyrion X.
- A Feast for Crows, Chapter 18, The Iron Captain.
- A Dance with Dragons, Chapter 27, Tyrion VII.
- The Mystery Knight.
- A Feast for Crows, Chapter 29, The Reaver.
- A Dance with Dragons, Chapter 26, The Wayward Bride.
- So Spake Martin: Kinslaying in Westeros (May 22, 2001)
- A Clash of Kings, Chapter 33, Catelyn IV.
- A Clash of Kings, Chapter 42, Davos II.
- A Storm of Swords, Chapter 70, Tyrion X.
- A Dance with Dragons, Chapter 32, Reek III.
- The Winds of Winter, The Forsaken
- A Storm of Swords, Chapter 20, Catelyn III.
- The World of Ice & Fire, Appendix: Stark Lineage.
- A Dance with Dragons, Chapter 46, A Ghost in Winterfell.
- A Game of Thrones, Chapter 30, Eddard VII.
- A Storm of Swords, Chapter 80, Sansa VII.
- A Feast for Crows, Chapter 23, Alayne I.
- A Clash of Kings, Chapter 51, Jon VI.
- The World of Ice & Fire, Viserys II.
- A Clash of Kings, Prologue.
- A Storm of Swords, Chapter 62, Jaime VII.
- A Dance with Dragons, Chapter 1, Tyrion I.
- A Dance with Dragons, Chapter 56, The Iron Suitor.