Earl Cowper (pronounced "Cooper") was a title in the Peerage of Great Britain. It was created in 1718 by George I for William Cowper, 1st Baron Cowper, his first Lord Chancellor, with remainder in default of male issue of his own to his younger brother, Spencer Cowper. Cowper had already been created Baron Cowper of Wingham in the County of Kent, in the Peerage of England on 14 December 1706, with normal remainder to the heirs male of his body, and was made Viscount Fordwich, in the County of Kent, at the same time as he was given the earldom, also Peerage of Great Britain and with similar remainder. He was the great-grandson of William Cowper, who was created a Baronet, of Ratling Court in the County of Kent, in the Baronetage of England on 4 March 1642. The latter was succeeded by his grandson, the second Baronet. He represented Hertford in Parliament. He was succeeded by his eldest son, the aforementioned William Cowper, the third Baronet, who was elevated to the peerage as Baron Cowper in 1706 and made Earl Cowper in 1718. In 1706 Lord Cowper married as his second wife Mary Clavering, daughter of John Clavering, of Chopwell, County Durham.
Lord Cowper was succeeded by his son, the second Earl. He assumed the additional surname of Clavering. Cowper married Lady Henrietta, younger daughter of Henry de Nassau d'Auverquerque, 1st Earl of Grantham, a relative of the Dutch House of Orange-Nassau, and a count of the Holy Roman Empire. On the death of Lady Cowper's elder sister, Lady Frances Elliot, in 1772, the second Earl's son, the third Earl became Lord Grantham's heir general, and on 31 January 1778 he was created a Prince of the Holy Roman Empire (Reichsfürst) by the Emperor Joseph II. He was allowed by George III to bear this title in Great Britain.