Game of Thrones Season 8 isn't like earlier seasons. There haven't been waves of casting announcements as new actors are hired to replace the characters killed off the season before, but that doesn't mean that the show is entirely devoid of new blood. After all, large armies in needed for massive battles, and when Daenerys burns up one, another has to be hired. That's where the Golden Company comes in. What is the Golden Company on Game Of Thrones? Warning: Spoilers for Game of Thrones Season 8 follow.
Last season, Cersei scored a pair of victories on Daenerys Targaryen, first taking out her navy and then a chunk of her army, when Tyrion attacked Casterly Rock. Daenerys responded by bringing the full force of her army to bear on the Lannister forces, in the "Wagon Loot Train" scene, which fans refer to as "The Field of Fire."
In response to losing so many men, Cersei immediate suggests to Jaime the answer is to hire more. She can bring over the Golden Company from Essos. They're mercenaries, but she'll pay them well, and in return, they'll fight for her. By the end of the season, she's sent Euron to do just that, and when the new season opens, he's come back with them.
Cersei's choice to hire the Golden Company isn't an accident. In the books, these are actually Westerosi fighters and their descendants. The Golden Company was first founded by Ser Aegor Rivers, a legitimized bastard of King Aegon IV. Rivers had chosen poorly, having backed Daemon I Blackfyre and his sons in the First Blackfyre Rebellion. When they were defeated, said Blackfyres and Rivers fled to Essos and created this group.
In the books, many Westerosi exiles wind up as part of the Golden Company, so much so it speaks volumes Viserys Targaryen didn't. In fact, both Jorah and Tyrion wind up as members for a time during A Dance With Dragons, traveling with the army to Meereen, as a way to get to Daenerys. Of course, all that was cut from the TV show, with Tyrion taking a far more direct route with Jorah.
Cersei's choice to bring over Westeros exiles has been a curious one to fans, who wonder if the move might backfire. After all, upon seeing the Night King, they all might turn and flee. But then again, they might decide they like Jon Snow and Daenerys Targaryen better and will be happy to fight for the new couple in exchange for being un-exiled.
Of course, that's assuming the show keeps that fact. Euron says something curious about the fighters on the ships being mutes, which does not track with the books at all. So perhaps the Golden Company has more up its sleeve than fans who have read the books expect.
Sadly, the Golden Company didn't bring their elephants to Westeros, since it would have been too difficult for the animals to make the journey. But the show will most likely put them into action sooner rather than later.