Natalie Dormer (TV's THE TUDORS) has signed onto the second season of HBO's smash hit series GAME OF THRONES, writes The Hollywood Reporter. She will play the conniving beauty, Margaery Tyrell, who sets out to marry King Robert’s brother Renly Baratheon in order to support Renly's campaign to take the crown from King Joffrey. The sci-fi drama is based on George R.R. Martin novel series.