Harriet Arbuthnot, English diarist (d. 1834)
Harriet Arbuthnot (10 September 1793 – 2 August 1834) was an early 19th-century English diarist, social observer and political hostess on behalf of the Tory party. During the 1820s she was the closest woman friend of the hero of Waterloo and British Prime Minister, the 1st Duke of Wellington. She maintained a long correspondence and association with the Duke, all of which she recorded in her diaries, which are consequently extensively used in all authoritative biographies of the Duke of Wellington.

Born into the periphery of the British aristocracy, her parents were Henry Fane and his wife, Elizabeth, née Swymmer; she married a politician and member of the establishment, Charles Arbuthnot. Thus well connected, she was perfectly placed to meet many of the key figures of the Regency and late Napoleonic eras. Recording meetings and conversations often verbatim, she has today become the "Mrs. Arbuthnot" quoted in many biographies and histories of the era. Her observations and memories of life within the British establishment are not confined to individuals but document politics, great events and daily life with an equal attention to detail, providing historians with a clear picture of the events described. Her diaries were themselves finally published in 1950 as The Journal of Mrs Arbuthnot.