Sir Jeffrey Gilbert (1674–1726) was an English barrister, judge and author who held office as Lord Chief Baron of the Exchequer in both Ireland and England, and later became renowned for his legal treatises, none of which were published in his lifetime.
He was born at Goudhurst in Kent, son of William Gilbert, a farmer, who died a few months after his son's birth; his mother Elizabeth Gibbon is said to have been a cousin of the great historian Edward Gibbon. He was called to the Bar in 1698 and earned some fame as a law reporter. He was an outstanding scholar, his interests including theology and mathematics as well as law: shortly before his death he became a Fellow of the Royal Society. He enjoyed the patronage of William Cowper, 1st Earl Cowper, and soon after Cowper's reappointment as Lord Chancellor, Gilbert in 1714 was sent to Ireland as a judge of the Court of King's Bench.
Soon after Gilbert's arrival in Ireland, the Chief Baron of the Irish Exchequer, Joseph Deane, died suddenly. It appears that no Irish-born judge had either the legal ability or the inclination to take on this extremely onerous appointment, which would involve clearing a large backlog of cases in the Court of Exchequer (Ireland) and reforming legal practices described by one of his fellow Barons of the Exchequer as creating "confusion and disorder almost beyond remedy". Accordingly, Gilbert, who was willing to take, and highly qualified for the office, received the promotion. His early years in Ireland were happy: he received an honorary degree from the University of Dublin and was hailed in ballads as the "darling of the nation".