Sir Gilbert Denys (c. 1350–1422) of Siston, Gloucestershire, was a soldier, and later an administrator. He was knighted by January 1385, and was twice knight of the shire for Gloucestershire constituency, in 1390 and 1395 and served as Sheriff of Gloucestershire 1393-4. He founded the family which provided more Sheriffs of Gloucestershire than any other.