Usurper is a derogative term that refers an individual who has seized power in opposition to a "legitimate" or "rightful" ruler who was perceived to have a better claim to the title.
Known uses of the term and other acts
- After ruling less than a year, King Orys I was assassinated by his own brother, who then usurped the throne.
- Queen Alicent Hightower usurps the throne for her son King Aegon II Targaryen while fully aware that her stepdaughter Rhaenyra Targaryen was the designated heir to her husband, Viserys I Targaryen, sparking the conflict known as the Dance of the Dragons.
- King Robert Baratheon is called "The Usurper" by Viserys and Daenerys Targaryen as well as by House Targaryen loyalists, because he technically usurped the Iron Throne from the Targaryens, even though his predecessor, Aerys II Targaryen, popularly called the Mad King, was by all accounts a cruel and unfit ruler. Those who helped Robert take the throne - Eddard Stark, Hoster Tully, Jon Arryn and Tywin Lannister - are disparagingly referred to as the "Usurper's dogs".
- Queen Cersei Lannister usurps the throne for her son Joffrey Baratheon while fully aware that he is not the son of Robert Baratheon and therefore has no claim to the throne. This continues with Tommen Baratheon, Joffrey's younger brother and heir, who becomes the new king after Joffrey is assassinated.
- Renly Baratheon attempts to take the throne for himself with the support of House Tyrell, despite knowing he is behind his older brother Stannis in line of succession since their "nephews" Joffrey and Tommen are actually bastards born of incest.
- Stannis Baratheon, the actual lawful heir of the late Robert, refers to the other four Kings in the War of the Five Kings - Joffrey, Renly, Robb Stark, Balon Greyjoy - as usurpers. Though Robb Stark and Balon Greyjoy do not lay claim to the Iron Throne, they seek to establish independent kingdoms, which Stannis considers as stealing the North and the Iron Islands from his kingdom.
- Roose Bolton and Walder Frey seize power in the North and the Riverlands respectively from House Stark and House Tully at the Red Wedding, where they murder Robb Stark and take Edmure Tully hostage.
- The Sand Snakes, led by Ellaria Sand, seize power in Dorne when they murder Prince Doran Martell and his son, Prince Trystane.
- Ramsay Bolton seizes power in the North from his father, Roose, when he murders him after the birth of his half-brother, whom he also murders along with his stepmother, Walda Bolton.
- Cersei later murders Queen Margaery Tyrell in the Destruction of the Great Sept of Baelor and inadvertently drives her son King Tommen Baratheon to commit suicide, leaving her free to usurp the throne for herself, however she has claims due to being Tommen's mother and right of conquest.
In the books
A great civil war between two rival branches of House Targaryen known as the Dance of the Dragons occurred from 129 to 131 AC (about 170 years before the War of the Five Kings). The late King Viserys I Targaryen had named his oldest surviving child as his heir: his daughter Rhaenyra. Rhaenyra was his only surviving child by his first wife, but he later remarried and had sons by his second wife, the eldest of whom was Aegon II. As soon as Viserys I died, Aegon II usurped the throne, though his supporters continued to insist that he was the rightful king because a younger son always inherits ahead of older daughters under the succession laws of the Andals and the First Men. The Targaryens were not from Westeros and the matter of royal succession was still somewhat unclear. Aegon II's faction therefore claimed that Rhaenyra was actually a usurper - even though her father had publicly declared her his heir and extracted oaths of loyalty from the major lords of the Seven Kingdoms years before to confirm her as his successor. During the Dance of the Dragons Rhaenyra's faction nicknamed Aegon II as "Aegon the Usurper".
In any event, both Rhaenyra and Aegon II actually died by the end of the Dance, leaving Rhaenyra's eldest surviving son Aegon III to succeed to the throne. Many saw this as a tacit legitimization of Rhaenyra's claim as the rightful monarch. However, following the Dance the Targaryens were so shaken that they wanted to ensure that such confusion would never occur again, so they enacted new special royal succession laws which explicitly stated that a female Targaryen can only inherit after all possible male heirs are deceased (including younger brothers, uncles, and distant cousins). Because Aegon III was trying to enforce this new principle, he could not hypocritically also say that it didn't apply to his own deceased mother - so the history books record that Aegon II was the official king at the time and that Rhaenyra was a rival claimant, or usurper (despite the fact that Rhaenyra managed to briefly capture King's Landing at one point and did indeed sit on the Iron Throne, briefly, before being driven from the city again). Had Aegon II been officially declared a usurper, Rhaenyra's son would have been called "Aegon II" and not "Aegon III", denying the legitimacy of his deceased uncle. Calling himself "Aegon III" may also have been a tactic to try to mend fences with his uncle's old supporters, by at least acknowledging him retroactively.
One of the major stigmas against bastard children is the fear that they, or their descendants, will eventually attempt to usurp their parents' trueborn heirs. Catelyn Stark was relieved when Jon Snow voluntarily joined the Night's Watch because it meant he was giving up all claim to land and title, and all threat was removed that he might one day attempt to usurp her son Robb Stark. These fears are not entirely ungrounded, as there are several infamous historical examples from Westeros in which bastard children became usurpers.
Probably the most notorious example is Daemon Blackfyre, the legitimized bastard son of King Aegon IV the Unworthy. Daemon was the greatest living warrior of his generation, and his father grew very attached to him. In contrast, Aegon IV's legitimate son was Daeron II, a not very martial man, but a wise and intelligent statesman and diplomat. Daeron II was years older than Daemon, so there was no question about the order of succession. Yet rumor spread that Daeron II was actually fathered by Aegon IV's brother Aemon the Dragon-Knight, and Daemon Blackfyre gathered many supporters to himself. Others insisted that Aegon IV himself started this rumor because he wished that Daeron II wasn't his own son, hating his bookishness and preferring the great warrior his bastard son Daemon was turning into. Daemon tried to usurp the throne in the Blackfyre Rebellion, the worst civil war that Westeros endured between the Dance of the Dragons and the War of the Five Kings. Ultimately he was defeated and killed at the Battle of the Redgrass Field, though Daemon's surviving sons from House Blackfyre would continue to harass the main line of the Targaryen dynasty for decades.
Many of these usurpers made claims about the lawful line of succession as a pretext to support their bids for power, but it is unclear if any truly believed them, or if they tried to take the throne simply because they could. Aegon II usurped the throne by arguing that under normal succession law a younger brother succeeds ahead of a younger daughter - even though his father had publicly named Rhaenyra as the lawful heir years before. Daemon Blackfyre was in a more difficult position because even though his taint of bastardy was legitimized by Aegon IV upon his deathbed, he was simply younger than Daeron II, even if he had been his trueborn full brother. The only option was to accuse Daeron II himself of being the bastard offspring of Queen Naerys and Prince Aemon, called the Dragonknight, who shared a close relationship.
When Cersei Lannister plotted to have her son Joffrey usurp the throne, the accusations of his alleged uncle Stannis Baratheon and Ned Stark - that the Queen had an incestuous affair with her own twin brother - seemed so outlandish that many initially waved them off as the flimsy justifications that past usurpers had used. Only gradually, as Joffrey's insanity became increasingly apparent, did more people gradually suspect that the accusations might be true. Nevertheless, a few who had known of Joffrey's true origins even before Jon Arryn - namely Pycelle, Varys, and perhaps even Littlefinger - kept the truth to themselves for their own purposes.