Brigitte Rousselot is a French noblewoman who appears in the final four episodes of The Tudors. A resident of the besieged city of Boulogne, she disguises herself as a man so that she can fight beside her father.
When the Duke of Suffolk and the Earl of Surrey are sent to contain a French breakout, they are ambushed by a large party of French soldiers, but nonetheless manage to gain the upper hand. After a ferocious duel, Charles finally manages to wound his opponent; one of the soldiers immediately rushes to his side, pulling off his cap to reveal that "he" is actually a young female in disguise. Charles immediately sheathes his sword and addresses her as "Mademoiselle", taking them both prisoner.
Brandon later speaks with Brigitte, whom he holds captive in his tent; he tells her her father is still alive, and that he will probably ransom her if a ceasefire is declared. Despite Charles providing her with food and drink, and not harming her, Brigitte is clearly afraid and suspicious. She angrily denounces the English as brutal raiders, describing their King, Henry VIII (who is Charles' best friend) as a self-destructive monster whom the French refer to as "The English Nero". Charles is indignant, but sadly concedes to himself that she is right, as he has been appalled by Henry's brutal, self-indulgent behavior for a long time. He asks about the suffering of civilians in Boulogne; Brigitte replies that they are all starving and eating whatever animals remain in the city, but they will never give in.
Charles later covertly releases Brigitte's father (who has recovered from his wounds) but keeps Brigitte captive; her father, seeing Charles as a chivalrous man, orders him to treat her with dignity, which Charles says he will. Later on, Brigitte comes to Charles as he sleeps, and they have sex. After the Siege of Boulogne, Charles prepares to head to England, and asks Brigitte to come with him. She asks him why, to which he smiles and replies in French: "I love you, that's all."
Brigitte becomes Charles' official mistress after they return to England (Charles has been estranged from his wife for several years) and tends to his health, which increasingly suffers. She also meets and befriends Charles' son Henry. Brigitte also attends the trial of the Earl of Surrey; when Surrey is convicted, Charles looks visibly pained, and Brigitte hugs him. Charles later tells her that, even as his and Henry's lives near their end, he worries more than ever about plots concerning Henry's throne, since the Protestant and Catholic factions of England each favor different heirs.
In the final episode, she tries to forbid the Earl of Hertford from visiting Charles (who is gravely ill) but Charles insists to her he is well enough to talk with Edward Seymour. When Charles dies, Brigitte closes his eyes and weeps at his deathbed. She is not seen again after Charles' funeral, although he likely left her financial assets to live on.