Colonel Fiennes Stanley Wykeham Cornwallis, 1st Baron Cornwallis, CBE, TD, JP, DL (27 May 1864 – 26 September 1935) was a British Conservative politician.

Lord Cornwallis was born 27 May 1864 at Chacombe Priory, Banbury, Oxfordshire, the eldest son of Fiennes Cornwallis^[1] and Harriet Elizabeth (née Mott). He had one brother and two sisters^[2] and was educated at Eton College.^[3]

He was elected to the House of Commons as Member of Parliament for Maidstone in 1888, a seat he held until 1895 and again from 1898 to 1900. He was also chairman of the Kent County Council between 1910 and 1930. In 1927 he was raised to the peerage as Baron Cornwallis,^[4] of Linton in the County of Kent, where his country house, Linton Park, was situated.

He was appointed Honorary Colonel of the Thames and Medway Heavy Brigade, Royal Artillery, on 11 March 1933.^[5]

Lord Cornwallis married Mabel Leigh, daughter of Oswald Peter Leigh, in 1886. They had seven children, three sons and four daughters. ^[6]

Fiennes Wykeham Mann Cornwallis was killed in Ireland in May 1921 during the Irish War of Independence. Lord Cornwallis was succeeded in the barony by his second son, Wykeham Stanley. Lady Cornwallis died in 1957.

Cornwallis was the grandson of Charles Wykeham Martin and great-grandson of James Mann, 5th Earl Cornwallis.

He was an eminent Freemason and was Provincial Grand Master of Kent and a Past Grand Warden ^[7] in the United Grand Lodge of England. Stanley Wykeham Lodge 6599 ^[8] was named for him.

• Kidd, Charles; Williamson, David (editors). Debrett's Peerage and Baronetage (1990 edition).
  New York: St Martin's Press, 1990. ISBN 0-333-38847-X