House of Montfort-Brittany
The House of Montfort-Brittany was a Breton-French noble family, which reigned in the Duchy of Brittany from 1365 to 1514. It was a cadet branch of the House of Dreux; it was thus ultimately part of the Capetian dynasty.
Source: Wikipedia — House of Montfort-Brittany (CC BY-SA 4.0)