William III, Count of Hainaut

William III of Avesnes (1286 - June 7 1337) was count of Hainaut and Holland from 1304 to his death, succeeding his father, John II. He married Joanna of Valois, sister of king Philip VI of France, in 1305 and had the following children:

• William IV of Hainaut (1307-1345)
• John (died 1316)
• Margaret II, Countess of Hainaut (1311-1356), married Louis IV Wittelsbach, Holy Roman Emperor
• Philippa of Hainault (1311-1369), married king Edward III of England
• Agnes (died 1327)
• Joanna of Hainaut (1315-1374), married William V, Duke of Jülich
• Isabelle of Hainaut (1323-1361), married Robert of Namur
• Louis (1325-1328)

See also: Counts of Hainaut family tree