Sarah Lyttelton, Baroness Lyttelton (néeSpencer) (29 July 1787 – 13 April 1870) was a British courtier, governess to Edward VII of the United Kingdom, and wife of William Lyttelton, 3rd Baron Lyttelton.
Lady Sarah Spencer was born at the Spencer seat of Althorp in Northamptonshire on 29 July 1787, and was the eldest daughter of the Whig politician Sir George Spencer, 2nd Earl Spencer (1758–1834) and his wife Lady Lavinia Bingham (1762–1831).
Sarah Spencer married Sir William Henry Lyttelton in March 1813, after an engagement of two months. He succeeded his half-brother to the barony of Lyttelton in 1828, upon which they began residing at Hagley Hall in Worcestershire. They had five children, two daughters Caroline (1816–1902) and Lavinia (1821–1850), and three sons George (1817–1876), Spencer (1818–1889) and William (1820–1884).
On 25 July 1839 her eldest son George (by then 4th Baron) married Mary, the daughter of Sir Stephen Richard Glynne, 8th Baronet. The marriage took place at Hawarden, the seat of William Ewart Gladstone who was simultaneously marrying Mary’s sister Catherine. George became a distinguished classical scholar like his father, but committed suicide in 1876 by throwing himself down the stairs. Sarah’s daughter, Lavinia, was later to marry Reverend Henry Glynne, brother of Catherine and Mary Glynne.