The earliest well-documented progenitor of this family was
Robert Lord of Cemais, whose charter to the monks at Montacute from around 1121 names his parents, Martin and Geva. Geva is known to have been the daughter and heiress of
Serlo de Burci, bringing the lands of her father to her marriage, which included Low Ham, Pylle, and Hornblotton. By her second marriage to
William de Falaise, which had occurred by 1086, she was to pass to her son and heir, Robert, additional land in Devonshire. From the patronymic of this Robert fitz Martin ("son of Martin") subsequent family members took 'fitz Martin' as a surname, independent of the names of their fathers, until in the mid-13th century, when they began to use simply Martin. Robert Fitz Martin succeeded to the lands which Serlo de Burci had held in 1086, and also to land held by his stepfather. He was a benefactor to various monasteries, giving land at Compton to Goldcilffe, the church of Blagdon to Stanley in Wiltshire, and the manor of Teignton to Montacute Priory in Somerset. He founded the abbey of St. Dogmael c. 1118. Not later than 1120, Robert Fitz Martin and Maud Peverel, his wife, granted to the abbey of Savigny land at Vengeons (la Manche) which had belonged to
William Peverel. In 1134, he joined with other Norman lords in South Wales in resisting the sons of Gruffydd, and witnessed several charters of the
Empress Maud, to whom he was adhered. In 1155,
Henry II confirmed to him the lands of his grandfather, Serlo de Burci, with all their liberties. Maud predeceased him, and he then married Alice de Nonant, daughter of Roger de Nonant, who survived him and remarried in or before 1175. ==William Fitz Martin (I)==