William Francis Cowper-Temple, 1st Baron Mount Temple, PC, known as William Cowper before 1869 and as William Cowper-Temple between 1869 and 1880, was a British Liberal statesman.

Earl Cowper 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.