Jean I d'Avesnes (1218-1257) was born 1 May 1218 in Houffalize, Belgium to Bouchard IV d'Avesnes (1182-1244) and Margaret II, Countess of Flanders (1202-1280) and died 24 December 1257 Valenciennes, France of unspecified causes. He married Aleid van Holland (bef1234-1284) 1246 JL .
Children
| Name | Birth | Death | Joined with |
| John II, Count of Hainaut (1247-1304) | 1247 | 22 August 1304 | Philippa of Luxembourg (1252-1311) |
| Boudewijn van Avesnes (aft1247-aft1299) | |||
| Johanna van Avesnes (?-1304) | |||
| Bouchard van Avesnes (1251-1296) | |||
| Guy d'Avesnes (c1253-1317) | 1253 | 23 May 1317 Utrecht, Netherlands | |
| Willem van Avesnes (1254-1296) | |||
| Floris van Avesnes (1255-1297) | |||
Footnotes (including sources)
| ‡ General |
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