The de Clare family name did not originate from any one particular person but rather from the name of the castle that King William awarded to his cousin, Richard FitzGilbert (b. 1015, d. 1090) who was the grandson of Geoffery, Count of D' Eu & Brionne (b. 953), for his cousin's loyalty and support. Often times, the names of individuals changed based on where they were born or the title they were given. Even in modern times this is true with the British Royal Family. Princes William and Harry took the name of 'Wales' since their father was the Prince of Wales, a title awarded to him by his mother, Queen Elizabeth II. 

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Count Geoffery's grandson, Richard FitzGilbert de Clare (b. 1035, d. 1090), is the first one to add 'de Clare' to his name taking the name 'FitzGilbert" meaning from Gilbert - his father was Gilbert of Brionne - and 'de Clare' from the name of the family castle, parts of which still exist as a park in the township of Clare. 

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On his death, Richard's English estates passed to his son Gilbert fitz Richard de Clare (1055-1117), while a younger son, Robert Fitz Richard, would give rise to a lineage that became Barons FitzWalter. A younger son of Gilbert fitz Richard, also named Gilbert, establishing himself in Wales, acquired the Earldom of Pembroke in 1138 and Lordship of Striguil. Earl Gilbert's nephew of the senior line, the son of his older brother, Richard Fitz Gilbert de Clare (1090-1136), would likewise be made an Earl. Gilbert fitz Richard (d. 1152) was named Earls of Hertford, perhaps in 1138 but at least by 1141, and subsequently the family would sometimes use the style of Earls of Clare. The first Earl of Hertford died without issue and was succeeded by his brother, Roger de Clare, 2nd Earl of Hertford, from whom the later Earls of Hertford descended.

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The son of Gilbert fitz Gilbert de Clare, Earl of Pembroke, was Richard de Clare, 2nd Earl of Pembroke (died 1176), known as Strongbow, a leader of the Norman invasion of Ireland. His only son died while still a minor, and Strongbow's many Irish and Welsh possessions passed with his daughter Isabel, to her husband, William Marshal.[

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The de Clare family became a wealthy and respected name in England. The Boggess family takes a slight turn from the de Clare family with the birth of Richard de Clare's daughter, Isabella de Clare (27th Great Grandmother, b. 1172, d. 1220). She was later to marry William Marshal (b. 1147, d. 1219). 

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