Dame Diana Rigg Joins Season 3 Of HBO's 'Game Of Thrones'

nullThe cult of "Game Of Thrones" grows ever stronger. Initially anticipated principally by fans of George R.R. Martin's books, the HBO series has won over more and more viewers since debuting last April, including many who would never have dreamed that they'd become hopelessly addicted to a fantasy series. And in part, it's thanks to the terrific cast, featuring a mix of veteran character actors (including the Emmy-winning Peter Dinklage), and bright new talent; every role has seemingly been cast impeccably, with a depth to its ensemble that few shows since "The Wire" can match.

Today at Comic-Con sees the show's panel as one of the main attractions in Hall H, and there's a good chance that some new cast members for Season 3 will be announced, but just ahead of it, the first addition to the next installment of the show has been revealed, in the shape of a true-blue geek icon. Baz Bamigboye reports that Dame Diana Rigg, who came to fame as the catsuited Emma Peel in cult spy series "The Avengers," before playing James Bond's ill-fated wife in "On Her Majesty's Secret Service," has joined the show in the role of Olenna Redwyne, the so-called Queen of Thorns.

Olenna is the grandmother of Margaery Tyrell (Natalie Dormer), a manipulative, powerful figure who's long been an expert of playing the game, and will arrive in King's Landing ahead of her granddaughter's wedding to the monstrous King Joffrey. Rigg's perhaps not been the most familiar face to U.S. audiences of late — her last major film role was in 2006's "The Painted Veil" — but her credits over the years have included "Theatre Of Blood," "A Little Night Music" and "The Great Muppet Caper," and she's remained active in British TV and theater.

Perhaps more importantly, she's a real geek icon thanks to her original role in "The Avengers," and she'll shore that up later in the year by starring alongside her daughter, Rachael Sterling, in an episode of "Doctor Who," so there'll be plenty who'll be thrilled with the casting. And it sounds like, in the broadest strokes, she's a perfect match for the part, although we're trying to avoid too much information about the character, having not read the book. Filming gets underway on Season 3 very shortly, and "Game Of Thrones" will return to screens next spring on HBO.

The image above, incidentally, is one of a series of new Comic-Con posters commissioned from collectible art supremos Mondo — head over to EW to look at more.