In the first of what is certain to be many casting announcements, Natalie Dormer has been added to Season 2 of Game of Thrones. She'll be playing Margaery Tyrell, the betrothed wife to a new contender for the throne.
Dormer is best known for her role as Anne Boleyn from Showtime's historical drama The Tudors, a role she played for two seasons. (At the very least, she'll be comfortable when the heads start flying in Westeros.) Dormer also had another period piece part in Casanova. She comes to Game of Thrones after landing the female lead in ABC's Poe, which wasn't picked up during pilot season.
Thrones fans wanting an early look at Dormer should keep an eye out during Captain America: The First Avenger, where she'll be playing "Private Lorraine."
Warning: Major Game of Thrones Season 1 spoilers as well as minor A Song of Ice and Fire (the overarching book series source material) plot details follow.
In George R.R. Martin's book series A Song of Ice and Fire, the character of Margaery is the only daughter of the Tyrell house which rules the powerful seat of Highgarden. She's also the sister to Loras Tyrell, also known as "The Knight of the Flowers," played by Finn Jones in the first season.
In the last episode of season one we see Robb Stark deciding between supporting two would-be kings against Joffrey: Robert Baratheon's younger brothers Stannis (middle) and Renly (youngest). We saw Renly this year as a member of the small council (played by Gethin Anthony). While Robb and the Winterfell banner men are fighting the Lannisters tooth and claw, Stannis and Renly are at a standstill, squabbling over who will take the war to King's Landing.
It's in this fray that Margaery Tyrell is introduced. She marries "King Renly" while he prepares for war with both Stannis and Joffrey. This is something of a conundrum, since Renly and Margaery's brother Loras have a... "special" friendship. Margaery becomes a major character in the book series, so Dormer's casting is pivotal.
The role of Stannis Baratheon, arguably the most important character introduced in the second book of A Song of Ice and Fire, has yet to be cast. Expect an announcement from HBO on this and other crucial roles very soon, as filming on the second season is set to start in July.
Season 2 of Game of Thrones is scheduled for spring of 2012 on HBO.