Robert de Bruce (Brus) was perhaps the son of Robert (or Adam) de Brus, who may have fought at the Battle of Hastings in 1066. Soon after September 1106, he might have been given eighty manors in Yorkshire from Henry I, as well as some around Skelton, and around 1119 he received Hart and Harness in Durham. He founded the Augustinian prior of Guisborough (Yorkshire) probably in 1119 - his brother, William, was the first prior. He may have had another brother, Peter. In 1124, David I granted Annandale to Robert, which the family kept for generations. He married Agnes, probable daughter of Geoffrey Bainard, sheriff of York, by whom he had two sons, Adam (d. 1143), and Robert (II). Robert died on 11 May 1142. A.A.M. Duncan, 'Robert (I) de Brus, lord of Annandale', ODNB, viii, 372; [http://www.oxforddnb.com/view/article/3748]