Game of Thrones star Sophie Turner admits to spoiling the ending

Sophie Turner has played Sansa Stark on Game of Thrones for eight seasons. Photo / supplied

Sophie Turner has told her friends how Game of Thrones ends.

The 22-year-old actress - who portrays Sansa Stark in the HBO drama series - admitted she is "terrible" at keeping secrets and couldn't even blame being drunk for giving the gossip on the eighth and final season of the show to her pals.

She said: "I'm so bad at keeping secrets. I don't think people tell me things anymore because they know that I can't keep them. I've already told the ending of Game of Thrones to a few people.

"[I was] sober. I was like, 'Hey, if you want to know, I'll tell you.' But it's people that I know, not random people. It's people that I know will keep the secret."

Sophie Turner says she's revealed the ending of the show to a number of people. Photo / AP

Turner - who is engaged to Joe Jonas - used to dye her hair red for the show, but in later series opted to wear a wig, and though it was easier to maintain, it's caused problems with her natural locks.

She told W magazine: "It gets very greasy. It never used to be like that. I think it's because I wear a wig on Game of Thrones, so the glue gets stuck in my hair, so I had to wash it every day and my hair is now used to that.

"If it's any longer than two days, it gets greasy."

The British star wasn't interested in keeping the wig and the only souvenir she took from the set was one of her raciest costumes, though she isn't too sure what to do with it.

She said: "I didn't want to keep [the wig]. I was like, 'Goodbye!'

"The only thing I kept was a corset from the show. I wouldn't have wanted that wig.

"I was thinking about framing it, but people might think it's a bit weird. Wearing it would be weird. And it's not the one that covers your boobs."