But it turns out *one* of the stars almost didn't make the cut after an innocent mishap.
Gemma Whelan, who plays Yara Greyjoy opened up about that time when she was almost high-key sacked from the role before she could even start.
"The first lesson I learnt was when I first got the job. No one told me to keep quiet about it," she told The Times.
"I just thought it was normal to pop it in my Spotlight entry, so I wrote on my CV, 'This summer, Gemma will be playing Yara Greyjoy in Game of Thrones.'"
Unsurprisingly, GoT fans were quick to spot Gemma's announcement and started posting updates online to alert everyone to the new casting.
"The internet went nuts. One of the lovely, lovely producers on Thrones called me into his office and said, 'This is very serious. We almost can’t employ you because of this.'"
Fortunately for Gemma, the GoT powers that be decided not to push the matter further and went ahead and hired her with just a warning.
This is a message for all of us, TBH.
Be V, V careful of what you post online - especially if you're ever cast in an epic TV series.
Ya know, just in case.