Richard Fitzgilbert De Clare, son of Gilbert Fitzgilbert De Clare and Isabel De Beaumont, was born in 1125 in Turnbrige, Kent, England and died on April 20, 1176 in Dublin, Leinster, Ireland at the age of 51. He married Aoife Macmurrough, daughter of Diarmait Macdonnchada Macmurchada and Mor O'toole, on August 26, 1171 in Waterford, Ireland. She was born about 1141 in Lancester, Lancastershire, England and died in 1177.

Isabel Fitzgilbert De Clare, daughter of Richard Fitzgilbert De Clare and Aoife Macmurrough, was born in 1174 in Pembroke, Pembrokeshire, Wales and died in 1220 in Pembroke, Pembrokeshire, Wales at the age of 46. She married William Marshall in August 1189 in London, England. He was born in 1144 in Pembroke, Pembrokeshire, Wales and died on May 14, 1219 in Caversham Manor, England at the age of 75.

Isabel Marshall, countess, daughter of William Marshall and Isabel Fitzgilbert De Clare, was born on October 9, 1200 in Pembroke Castle, Pembrokeshire, Wales and died on January 15, 1239 in Berkhamstead, Hertfordshire, England at the age of 38. She married Gilbert De Clare, son of Richard De Clare and Amicia Fitzrobert, on October 9, 1217 in England. He was born in 1182 in Hertford, Herfordshire, England and died on October 25, 1230 in Penrose, Brittany, France at the age of 48.