William I, Count of Hainaut Count of Holland, Zeeland and Hainaut (1287–1337) (1287–1337) Parents Philippa of Luxembourg John I of Hainaut Children Margaret II, Countess of Hainaut Jan Aelman Philippa of Hainault Isabella d'Avesnes Catherine d'Avesnes Joanna of Hainaut William II of Hainaut Siblings John of Beaumont Alice of Hainault Mary of Avesnes Isabelle of Avesnes Jan van Oostervant Willem Cuser Aleida de Hainaut Simon Heer van Bruelis Marguerite d'Avesnes Partners Joan of Valois, Countess of Hainaut
