Dame Diana Rigg has died at the age of 82, the actor's agent confirmed to the BBC.
Her agent told the publication: "She died peacefully early this morning. She was at home with her family who have asked for privacy at this difficult time."
She was known for roles including Emma Peel in TV series The Avengers between 1965 and 1968, and the wife of James Bond in 1969 film On Her Majesty's Secret Service.
Younger viewers will also know her as Olenna Tyrell from Game of Thrones, who she played for five years between 2013 and 2017.
Rigg first found fame in the 1960s with The Avengers, and went onto to portray Tracy Bond - one of the most famous Bond girls of all time, as she was the only woman 007 has married.
But Rigg, who was born in Doncaster in 1938, found she particularly enjoyed her time on HBO fantasy series Game of Thrones.
Reflecting on her career last year, she told the BBC: "I love playing bad [characters].
"They are so much more interesting than good.
"There are some actors who don't like to play bad; they like to be liked. I love to be disliked. Olenna had the best lines, they were very kind with their scripts."
Rigg admitted she had no idea just how popular Game of Thrones was when she was offered the role, continuing: "The world turns full circle, because just like with The Avengers, I wasn't watching Game of Thrones and had absolutely no idea of its influence in the world.
"It was a job, they sent me a script, and I thought 'I can do this.'
"Interestingly enough, they tested me very early on.
"One of my earliest scenes was incredibly difficult, listing all the things my marching army would need.
"It went on forever, talking about the sheep and the cows and the soldiers. I read that and thought, 'these guys are testing an old actress to see if she can get it into her head.'
"I thought, 'I'm going to do it in one take.' And I did."
Rigg was nominated Emmys in 2013, 2014 and 2015 for her recurring role in the show.