Isabel FitzWilliam of Gloucester, Countess of Gloucester, was born circa 1173 to William Fitz Robert, 2nd Earl of Gloucester (-1183) and Hawise de Beaumont (c1125-c1172) and died 14 October 1217 of unspecified causes. She married John of England (1167-1216) 29 August 1189 JL . She married Geoffrey de Mandeville (c1191-1216) 20 January 1214 JL . She married Hubert de Burgh (c1160-c1243) 1217 JL . William I of England (1027-1087)/s.