John Southerden Burn (3 July 1798 – 15 June 1870) was an English solicitor and antiquary.
Burn was the son of Captain John Southerden Burn of the Royal Marines and his wife Ann Ralph, daughter of Edward and Elizabeth Ralph. He qualified as a solicitor in 1819, when he began to practise at 11 Staple Inn, Holborn in London. In 1820 he moved to 11 King's Bench Walk, Temple, and in 1822 to 27 King Street, Cheapside. In the following year he entered into a partnership with Samuel Woodgate Durrant, which lasted till 1828, when he removed to 25 Tokenhouse Yard.
In 1831 Burn was appointed registrar of marriages at chapels prior to 1754. In 1836 he became secretary to the commission for inquiring into non-parochial registers, a post which he retained until 1841. In that year he moved to 1 Copthall Court, Throgmorton Street, and entered into a partnership with Stacey Grimaldi and Henry Edward Stables, which lasted until 1847, when Grimaldi retired. In 1854 a new partner, Charles Tayler Ware, joined the firm; in the following year, after Stables's death, Burn retired from practice, and lived at The Grove in Henley-on-Thames.
Burn died at The Grove at the age of 71.
Burn married firstly Sarah Sophia Colnett at St Lawrence Jewry on 17 April 1822. They had a daughter Ellen, but Sarah died. He married secondly Jane Norton (1815-1899), and a marriage settlement was made on 27 September 1848. They had children Stacey, a doctor, John a clergyman and Ann. He was the grandfather of John Burn Olympic rower, and cousin of Edmund Blacket Australian architect. He was also uncle by marriage of Christiana Edmunds.
Professionally concerned with parish registers, he studied them. Finding that no specialist work on the area had appeared since Observations on Parochial Registers (1764) by Ralph Bigland in 1764, he published in 1829 his Registrum Ecclesiæ Parochialis, a history of parish registers in England, with observations on those in other countries. A second edition appeared in 1862. In 1831 he published, with biographical notes, the Livre des Anglois à Genève, the register of the English church in Geneva from 1554 to 1558, which had been communicated to him by Samuel Egerton Brydges.