Gilbert de Clare, 8th Earl of Gloucester, 7th Earl of Hertford 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.

Gilbert de Clare, 6th Earl of Hertford, 7th Earl of Gloucester was a powerful English noble. He was also known as "Red" Gilbert de Clare or "The Red Earl", probably because of his hair colour or fiery temper in battle. He held the Lordship of Glamorgan which was one of the most powerful and wealthy of the Welsh Marcher Lordships as well as over 200 English manors.