Constance Penthièvre de Bretagne, Duchess regnant of Brittany, Countess regnant of Richmond, was born 12 June 1161 to Conan IV de Bretagne (c1138-1171) and Margaret of Huntingdon (1140-1201) and died 5 September 1201 of unspecified causes. She married Geoffrey, Duke of Brittany (1158-1186) 1181 JL . She married Guy de Thouars (c1254-1213) 1198 JL . Alfred the Great (849-899)/s, Charlemagne (747-814)/s, Hugh Capet (c940-996)/s, William I of England (1027-1087)/s, Rollo of Normandy (860-932)/s.
|Offspring of Constance de Bretagne and Geoffrey, Duke of Brittany (1158-1186)|
|Eleanor, Countess of Richmond (1184-1241)||1184||10 August 1241|
|Matilda of Brittany (c1185-c1185)|
|Arthur I, Duke of Brittany (1187-1203)||29 March 1187||1203|
|Offspring of Constance de Bretagne and Guy de Thouars (c1254-1213)|
|Alix de Thouars (1201-1221)||1201||1221||Pierre I de Bretagne (c1187-1250)|
|Catherine de Thouars (1201-c1239)|