In the first casting announcement for Game of Thrones' forthcoming second season, it has been confirmed that actress Natalie Dormer will be playing Margaery Tyrell.
Natalia Dormer is an English actress with a string of credits to her name (including an appearance in the forthcoming Captain America movie), but is best-known for playing Anne Boleyn on the first two seasons of The Tudors. Her performance on the show was particularly acclaimed.
On Thrones, she will be playing Margaery Tyrell, the daughter of Lord Mace Tyrell and brother to Ser Loras Tyrell. In the books she is part of the intrigue put in motion by Mace as he attempts to attach his family to the Iron Throne, first as part of an abortive plot to have Robert divorce Cersei and marry Margaery instead (a plot wholly absent from the TV series) and later using her as a pawn when Renly Baratheon (Loras' lover) claims the Iron Throne.
According to the report, Dormer will be joining the show's regular cast, which is surprising news, given that Margaery is barely in the second book and doesn't really start playing a major role until the fourth. This move, as well as the casting of a reasonably well-known actress from another successful TV show, suggests that Margaery's role is being beefed up for the TV series. Exactly how much her role is increased by remains to be seen.