- Davos: "Westeros is not the world, your grace. We need to look east for ships and men. Ten thousand skilled soldiers fight for the Golden Company."
- Stannis: "The Golden Company?!"
- Davos: "They've never broken a contract."
- Stannis: "They're sellswords!"
- Davos: "We're willing to use blood magic to put you on the throne, but we're not willing to pay men to fight?!"
- — Davos Seaworth and Stannis Baratheon[src]
The Golden Company is a sellsword company active in Essos. They are one of the largest and most skilled sellsword companies in the Free Cities, consisting of 10,000 infantry, cavalry, and war elephants. They have the reputation of never breaking a contract, which is quite uncommon among mercenary organizations.
Their current leader is Harry Strickland.
The Golden Company was founded by supporters of House Blackfyre, a cadet branch of House Targaryen, which tried to seize the Iron Throne in the Blackfyre Rebellion, a century before the War of the Five Kings. When they lost, many Blackfyre supporters fled into exile in the Free Cities, where they formed their own sellsword company in order to survive, and remain a cohesive fighting force to launch future rebellions with (which all failed). The sons and grandsons of these Westerosi exiles were later raised to take their place in this mercenary army, supplemented by other men over the generations who were on the losing side of one war or another and fled into exile - mostly from Westeros, but also men from all over the world.
In time, these soldiers of fortune rose to become the best and largest sellsword company in the Free Cities, a large private army for hire, commanded by its own officers.
Davos Seaworth suggests to Stannis Baratheon that he hire the Golden Company to help him win the Iron Throne. Stannis refuses, believing sellswords to be unfit to join his army. Davos finds it hypocritical that Stannis would use blood magic to win the throne but not pay men to fight.
When Jorah Mormont advises Daenerys Targaryen not to trust Daario Naharis because he is a sellsword, she points out that he himself fought for the Golden Company before pledging his sword to her brother Viserys.
Having openly seized the throne, Queen Cersei Lannister intends to take out a new loan from the Iron Bank of Braavos to hire the Golden Company, to bolster the Lannisters' military forces, which have become badly depleted after years of war. 
The largest sellsword company in the Free Cities, the Golden Company is a large private army operating under its own officers and command structure. Its well-equipped forces consist of 10,000 men, including foot soldiers, archers, cavalry, and even war elephants.
- In Season 3's "Breaker of Chains", Davos and Stannis stated that the Golden Company consists of 10,000 men - which is accurate to the number given in the books. In the Season 7 finale, however, Cersei Lannister said that they have 20,000 men - contradicting a number already given in TV series dialogue. While it's not impossible that the Golden Company could hire more men with a bank loan, the TV writers may have confused this with a different quote from the novels, when Stannis orders one of his subordinates to hire at least 20,000 mercenaries, including the Golden Company's 10,000 (providing that they are available). The Season 7 finale "The Dragon and the Wolf" actually had multiple number errors like this, contradicting information from the books which had already been stated on-screen in earlier TV seasons (Tyrion says King's Landing has a population of one million, even though in Season 3 Jaime stated that it is half a million, as in the books). The TV writers might just be making a loose retcon, ignoring that they already said the Golden Company has 10,000 men in it. For the moment, Game of Thrones Wiki will consider Cersei's line in the Season 7 finale to be a dialogue error (or that, in-universe, Cersei the fictional character got her facts wrong). If Season 8 consistently gives their number as 20,000, this will be updated as an official, intentional retcon.
In the books
In the A Song of Ice and Fire novels, the Golden Company was founded one hundred years before the War of the Five Kings by Aegor Rivers, aka "Bittersteel", one of the bastard sons of King Aegon IV Targaryen, after he fled Westeros following the First Blackfyre Rebellion.
House Blackfyre was a younger cadet branch of House Targaryen founded by Aegon IV's bastard son Daemon Blackfyre. The first rebellion ended with Daemon's death, but his sons and half-brother Bittersteel fled into exile. When Aegor, who for a time served with the Second Sons, saw all the exiled lords and knights signing on with other sellsword companies, and saw the support of House Blackfyre ebbing away, he created his own sellsword company. That way, the Blackfyres could at least maintain some sort of core fighting force in between their repeated attempts to overthrow the Targaryens, gaining experience from fighting in the petty wars of the Free Cities, as well as gaining enough money from their contracts to keep functioning.
Their motto is "Our word is as good as gold", while their battle cry is "Beneath the gold, the bitter steel!" - in reference to their founder, Bittersteel. According to a preview chapter from the sixth novel, their Heraldry is a solid gold banner, unblazoned.
The Golden Company's reputation was quickly established when, soon after the company's founding, Qohor refused to honor the contract it had made. The sellswords of the Golden Company sacked Qohor as an answer to Qohor's refusal.
The Golden Company did not take part in the "Second Blackfyre Rebellion", which was really more of a short lived plot than a battle (much less a war), but it did take part in the Third Rebellion, and then the Fourth Blackfyre Rebellion, an invasion which landed in Massey's Hook (the southern Crownlands, near the northern Stormlands) but which was not very successful. During the fifth and last Blackfyre rebellion, known as the War of the Ninepenny Kings, the Golden Company formed one of the core parts of the Blackfyres' forces in the Stepstones, but they were defeated by the young Brynden Tully and Barristan Selmy.
At the time of the War of the Five Kings, the Golden Company is the largest and best disciplined sellsword company in the Free Cities, functioning as an elite private army. Their forces consist of 10,000 men: 1,000 cavalry, 1,000 archers, and 8,000 infantry, as well as a number of war elephants. About 50 of their archers are Summer Islanders, considered the best archers in the known world, armed with large and incredibly strong bows made of Goldenheart wood. As a large private army, they function under their own command structure of officers and serjeants. By the time of the novels, their commanders include:
- Harry Strickland, called Homeless Harry, the current company commander. His great-grandfather was part of the original group of Blackfyre supporters who founded the Golden Company. Formerly the company paymaster, he is not much of a warrior.
- Laswell Peake, Marq Mandrake, and Tristan Rivers - Strickland's main lieutenants, commanding subdivisions of their main army. All are exiled Westerosi knights.
- Black Balaq, commander of the company archers. A Summer Islander.
- Lysono Maar, company spymaster. A Lysene man with pronounced Valyrian features, flamboyantly dressed in effeminate makeup, and considered to be more beautiful than many women.
- Gorys Edoryen, company paymaster. A Volantene man with blood-red hair and cadaverous features.
The company is composed mostly of Westerosi exiles, and sons of exiles. Many of the core members are descended from the hundreds of Blackfyre supporters who fled across the Narrow Sea at the end of the First Blackfyre Rebellion. Over the past century their ranks were joined by other men who ended up on the losing side of rebellions in Westeros, who fled to the Free Cities to nurse dreams of reconquest rather than face execution or exile to the Night's Watch.
The Golden Company is first mentioned in the fourth novel. It is repeatedly rumored that the company has broken its contract with Myr; as strange as it sounds, despite the company's reputation, it turns to be correct, but no one knows for sure the reason. The Small Council receives questionable reports that Stannis has hired them, and intends to bring them across the Narrow Sea. Cersei dismisses that as nonsense (for a change, she is correct), because Stannis does not have enough money to hire the company, and they are sailing to Volantis - the opposite way.
The Golden Company becomes actively involved in the plotline during the fifth novel. An envoy from Yunkai is sent to hire them for the campaign against Daenerys, offering twice what Myr was paying them. Although he does not intend to accept the offer, the commander Harry Strickland tells the envoy evasively he'll consider it, thinking that a blunt refusal would make his men think he has lost his mind.
In a sample chapter of the sixth novel, Stannis meets Tycho Nestoris, and finally receives the funds he needs to hire reinforcements. He order Ser Justin Massey to travel to Braavos and hire 20,000 sellswords, preferably the Golden Company, unless they are already under contract.
Daenerys recalls that years ago, Viserys feasted the captains of the Golden Company, hoping they might take up his cause. They ate his food, heard his pleas - and laughed at him.
In the novels there is no mention of Jorah Mormont having been a member of the Golden Company, though it is said that after fleeing into exile he drifted around as a sellsword for several years. There is also no specific mention in the novels of the Golden Company being hired by the Iron Bank of Braavos to collect debts - though many wars in the Free Cities are fueled by such trade wars, and sellswords will fight for whoever pays them.