The youngest child of Lord Mace Tyrell, Margaery is a pretty young woman who is similar enough to her famed brother, Ser Loras, that some say they might as well be twins. She has the curling brown hair of the Tyrells, with brown eyes.
When introduced, Margaery is only fifteen years old, but the actress playing her part is nearly twice that age, and she is also rather older than Finn Jones, who plays Ser Loras. Will Margaery’s age be brought up to reflect this, perhaps making her an older sister? Also, photos of Ms. Dormer during production show her with blond hair, so it’s unclear whether she will retain Margaery’s hair color.