Peter I, Duke of Brittany

Peter I
Peter represented on a window in Chartres Cathedral
Duke of Brittany
Reign	1213–1221 (as duke) 1221–1237 (as regent)
Predecessor	Alix
Successor	John I
Co-ruler	Alix
Born	c. 1187
Died	26 May 1250 (aged 63)
Spouses	Alix, Duchess of Brittany Nicole Margaret of Commequiers
Issue	John I, Duke of Brittany Yolande, Countess of Penthièvre Arthur Oliver I of Machecoul
House	Dreux
Father	Robert II, Count of Dreux
Mother	Yolande de Coucy

Peter I (French: Pierre; c. 1187 – 26 May 1250), also known as Peter Mauclerc, was Duke of Brittany jure uxoris from 1213 to 1221, and regent of the duchy for his minor son John I from 1221 to 1237. As duke he was also 1st Earl of Richmond from 1218 to 1235.