Mabel FitzRobert, Countess of Gloucester

Mabel FitzRobert, Countess of Gloucester (c. 1100 – 29 September 1157) was an Anglo-Norman noblewoman, and a wealthy heiress who brought the lordship of Gloucester, among other prestigious honours to her husband, Robert, 1st Earl of Gloucester upon their marriage. He was the illegitimate son of King Henry I of England. 
Her father was Robert Fitzhamon, Lord of Gloucester and Glamorgan. As she was the eldest daughter of four, and her younger sisters had become nuns, Mabel inherited all of his honours and properties upon his death in 1107.
As Countess of Gloucester, Mabel was significant politically and she exercised an important administrative role in the lordship.
Family.
Mabel was born in Gloucestershire, England c. 1100, the eldest of the four daughters of Robert FitzHamon, Lord of Gloucester and Glamorgan, and his wife, Sybil de Montgomery. Her three younger sisters, Hawise, Cecile and Amice all became nuns, making Mabel the sole heiress to her father's lordships and vast estates in England, Wales, and Normandy.
Her paternal grandfather was Hamon, Sheriff of Kent, and her maternal grandparents were Roger de Montgomery, 1st Earl of Shrewsbury and Mabel de Bellême.
In March 1107, her father died in Normandy, leaving his lordships and estates to Mabel. Her mother married secondly Jean, Sire de Raimes.
Marriage.
In June 1119, Mabel's marriage to Robert of Caen (also called FitzRoy and FitzEdith), an illegitimate son of King Henry I (not by his mistress Sybil Corbet - other sources say Robert's mother was of the Gai family of Oxfordshire), was solemnized. Their marriage may have been contracted as early as 1107 and is recorded by "Orderic Vitalis" who also names her parents. He would later become an important figure during the turbulent period in English history known as The Anarchy which occurred in the reign of King Stephen of England. Throughout the civil war, he was a loyal supporter of his half-sister Empress Matilda who would make him the chief commander of her army. He had originally sworn fealty to King Stephen, but after quarrelling with him in 1137, his English and Welsh possessions were forfeited, and thus he joined forces with Matilda.
Countess of Gloucester.
Mabel brought to her husband the honours of Gloucester in England, Glamorgan in Wales, Sainte-Scholasse-sur-Sarthe, Evrecy and Creully in Normandy. By right of his wife, he became the 2nd Lord of Glamorgan, and gained possession of her father's castle of Cardiff in Wales. In August 1122, he was created 1st Earl of Gloucester; henceforth, Mabel was styled as Countess of Gloucester. 
As countess, Mabel exercised a prominent administrative role in the Gloucester lordship. Her political importance was evident when she was made responsible for seeing that her husband upheld his side of the agreement in the treaty he made with Miles de Gloucester, 1st Earl of Hereford. She also witnessed four of Robert's charters; as well as giving her personal consent for his foundation of the Abbey of Margam, whose endowment came from her own lands. Later, after Robert's death, Mabel assumed control of the honour of Gloucester's Norman lands on behalf of her eldest son William.
Issue.
Together Robert and Mabel had at least eight children:
Robert also sired an illegitimate son, Richard, Bishop of Bayeux by Isabel de Douvres.
Death.
Mabel's husband died on 31 October 1147. Mabel herself died on 29 September 1157 in Bristol at the age of sixty-seven years. She was buried at St James' Priory, Bristol.