Sarah Harriet Burney (29 August 1772 – 8 February 1844) was an English novelist, the daughter of musicologist and composer Charles Burney, and half-sister of the novelist and diarist Frances Burney (Madame d'Arblay).
Sarah Burney was born at Lynn Regis, now King's Lynn and baptised there on 29 September 1772. Her mother, Elizabeth Allen, was the second wife of Charles Burney, and relations within the family were often strained. Sarah was brought up in Norfolk by relations of her mother until 1775, when she joined the Burney household in London. This homecoming is described in a letter from Frances Burney to the dramatist Samuel Crisp: "Now for family.... Little Sally is come home, and is one of the most innocent, artless, queer little things you ever saw, and altogether she is very sweet, and a very engaging child." In 1781 she was sent with her brother Richard (1768–1808) to Corsier-sur-Vevey, Switzerland, to complete her education and probably returned in 1783. She gained an excellent knowledge of French and Italian, and acted as an interpreter for French refugee nobles on several occasions.
As an adult Burney alternated between nursing her elderly parents in Chelsea (her mother up to 1796, her father from 1807 to 1814) with periods as a governess and companion, as she was far from wealthy. Life with an ill-tempered father suited Burney even less after her mother died. Her half-brother Rear Admiral James Burney (1750–1821), who had separated from his wife, wished to move back in with his father and sister, but his father would not allow it. So there was family consternation when Sarah and James absconded together and spent the years 1798 to 1803 living in some penury in Bristol and then London. It has even been suggested that their relationship was incestuous. This assumption has been challenged in some detail in a more recent, closely researched account of Burney's life and personality. Study of Sarah's surviving bank statements shows also that her small wealth was much depleted during this period.
In 1807, Sarah Burney moved back again to nurse Charles Burney. Her relations with her father remained poor and she inherited very little from him when he died in 1814, although she had worked hard as his housekeeper and amanuensis. She lived in Italy from 1829 to 1833, mainly in Florence. There is an appreciative description of her in the diary of H. Crabb Robinson, who met her in Rome in 1829. She coincided in Italy with her niece and favourite correspondent, Charlotte Barrett (1786–1870), who was there to nurse her two daughters, who had tuberculosis. One of them died, but the other, Julia Maitland, later made a full recovery. It is unclear why Sarah Burney's relationship with her niece cooled for some years after that period, but it may have been because she was felt not to have given the Barretts all the practical help that they needed in Italy.