John Armstrong (22 August 1813 – 16 May 1856) was a Church of England cleric who became the Bishop of Grahamstown in South Africa.

Armstrong was born in Bishop-Wearmouth on 22 August 1813, the second child and eldest son of a physician who had settled in London around 1818.

He went in 1832, when nearly 19 years of age, to a private tutor, the Revd James Tweed, of Harlow, Essex, with the view of fitting himself to become a candidate for Lord Crowe's Exhibition at Lincoln College, Oxford.

His further object was the successful founding of St. Andrew's College, Grahamstown, in 1855, whose dedication commemorates the date of his consecration.

[2] But the rough travelling and many anxieties of his diocese were too severe for the bishop's delicate frame and he died on 16 May 1856 after less than two years in the country.