Alix of Thouars

Alix of Thouars (1200–1221) became duchess of Brittany as an infant in 1203, after her captive half-brother Arthur disappeared in John of England's prisons and Breton barons set aside her half-sister Eleanor's claim. Her father Guy of Thouars ruled as regent until 1206, when Philip II of France took over and in 1213 married her to his cousin Peter of Dreux, called Mauclerc.

Peter governed the duchy in her name. Alix died in 1221, leaving the duchy to her infant son John I.