Robert of Thornham (or Robert de Turnham) (died 1211) was an English soldier and administrator. The namesake of his landowner father, he was the younger brother of Stephen of Thornham. Robert made his reputation in connection with the conquest of Cyprus in 1191 during the Third Crusade. On order of King Richard I, he led half the fleet in that battle. Subsequently, he was responsible for controlling the island when the Crusaders moved on, first jointly with Richard de Camville and then independently, when he defeated a group of Cypriot rebels. After he left Cyprus, Robert became more closely identified with Richard I. As the king's familiaris, he carried Richard's equipment from the Holy Land to England. When Richard I was captured in 1192 in Vienna, among the terms of his release was the presentation of men to stand as "pledges" that the ransom would be paid. Robert was among these hostages, though evidently not for long, as he was back by the king's side in 1194 at Poitiers. Appointed Seneschal of Anjou, he served in France with Richard I, primarily in Anjou and Normandy, throughout the rest of Richard's reign. At around the same time, he was also appointed High Sheriff of Surrey, but he did not return to England until after Richard's death. In 1196, he led troops at Richard's behest into Brittany on an unsuccessful attempt to capture the child Duke of Brittany Arthur, whose mother Constance was resistant to Richard's control. In 1197, King Richard arranged for Robert to marry Isabella Fossard, daughter and heiress of the powerful Yorkshire baron William Fossard. The Fossard inheritance included the castle, honor, and lordship of Mulgrave with 34.5 attached knight's fees.