Harriet Monsell (1811 – 25 March 1883) founded the Community of St John Baptist, an order of Augustinian nuns in the Church of England dedicated to social service, which by her death had expanded to numerous houses, including in India and the Americas.

Her father, Sir Edward O'Brien, 4th Baronet of Dromoland, continued family tradition by representing his county Clare in Parliament until 1826, when he relinquished the seat to his son for health reasons.

He was the third son of the Archdeacon of Derry, Thomas Bewley Monsell, and upon ordination was licensed to his father's curacy and later received a prebendary at Limerick Cathedral.

She began working in Clewer near the garrison town of Windsor among former prostitutes and unwed mothers at a House of Mercy, which had been founded by Mrs Mariquita Tennant (1811-1860), a Spanish refugee and convert to Anglicanism (and clergyman's widow) several years earlier.

She thus became Mother Superior of the Community of St John Baptist, established on 30 November 1852, and one of the first Anglican religious orders since the Reformation.

[6] By T. T. Carter's death in 1901, the Community of St John Baptist had more than 300 members in Great Britain, India and the United States.