Yolande of Aragon

Queen Yolande of Aragon' (11 August 1384 – 14 November 1442) was a throne claimant and titular queen regnant of Aragon, titular queen consort of Naples, Duchess of Anjou, Countess of Provence, and regent of Provence during the minority of her son. Yolande played a crucial role in the struggles between France and England, influencing events such as the financing of Joan of Arc's army in 1429 that helped tip the balance in favour of the French.

Secretly, Yolande was also the Mentor of the French Brotherhood of Assassins, using her influence over her dull son-in-law, the future King Charles VII of France, to prevent the Templars controling England to take back France after the purge of the Templars a century before.

Reference

 * Assassin's Creed: Heresy