John Mainwaring (1724–1807) was an English theologian and the first biographer of the composer Georg Friedrich Händel in any language. He was a Fellow of St. John's College, Cambridge, and became rector of the parish of Church Stretton, Shropshire, and, later professor of Divinity at Cambridge. In 1760, one year after Handel was buried in Westminster Abbey he published anonymously a biography 'Memoirs of the Life of the Late George Frederic Handel'.
More than half of this biography is focused on the years before 1712, when Handel moved to London. Therefore it is supposed he received information from Handel himself on his early life or from John Christopher Smith. The Catalogue and the Observations are additions to the Memoirs by other authors. Charles Jennens owned a copy of the Memoirs, and provided the book with critical remarks on Semele and Benedetto Pamphili.
In 1761 Johann Mattheson published an extended translation with sharp remarks on the biography of Mainwaring.
Facsimile reprints of the "Memoirs" were published in 1964 and 1975.
- Memoirs of the Life of the Late George Frederic Handel: To which is Added a Catalogue of His Works and Observations Upon Them, R. and J. Dodsley, 1760.
- Handel. A Celebration of his Life and Times, 1685-1759, p. 236.
- Donald Burrows. Handel. Oxford University Press, 1994. Page 465. ISBN 978-0-19-816649-8
- Donald Burrows. Handel. 1994, p. 3.
- Beeks, Graydon (1995), Memoirs of the Reverend John Mainwaring, a Handelian biographer, Festa musicologica: essays in honor of George J. Buelow, Pendragon Press, pp. 79–101, ISBN 094519370X