Gilbert de Clare, 8th Earl of Gloucester, English commander (b. 1291)
Gilbert de Clare, 8th Earl of Gloucester, 7th Earl of Hertford (c. 10 May 1291 – 24 June 1314) was an English nobleman and military commander in the Scottish Wars. In contrast to most English earls at the time, his main focus lay in the pursuit of war rather than in domestic political strife. He was the son of Gilbert de Clare, 7th Earl of Gloucester, and Joan of Acre, daughter of King Edward I. The older Gilbert died when his son was only four years old, and the younger Gilbert was invested with his earldoms at the young age of sixteen. Almost immediately, he became involved in the defence of the northern border, but later he was drawn into the struggles between Edward II and some of his barons. He was one of the Lords Ordainers who ordered the expulsion of the king's favourite Piers Gaveston in 1311. When Gaveston was killed on his return in 1312, Gloucester helped negotiate a settlement between the perpetrators and the king.

Now one of Edward's strongest supporters, he accompanied the king on a campaign to Scotland in 1314, when several other nobles refused. He was killed at the Battle of Bannockburn on 24 June, under somewhat unclear circumstances. Gloucester was the most prominent of the casualties of the battle, which ended in a humiliating defeat for England. As he had no issue, his death marked the end of the prominent de Clare family. His estates were divided between his three sisters, one of whom was married to the king's new favourite, Hugh Despenser the younger. Despenser's ruthless expansion of the de Clare Lordship of Glamorgan in Wales led directly to the troubles of Edward II's later reign, including a rebellion in the Welsh Marches, the defeat of the Earl of Lancaster at the Battle of Boroughbridge, and eventually the deposition of the king by Roger Mortimer and Queen Isabella in 1326.