John Armstrong (22 August 1813–1856) was a Church of England clergyman and bishop of Grahamstown.
He was educated at a preparatory school in Hanwell before being sent to Charterhouse School. In 1832, he went to Lincoln College, Oxford, graduating in 1836 with a third-class honours degree in Classics. He was ordained in the Church of England in 1837.
He founded St. Andrew's College, at Grahamstown, in the Colony of the Cape of Good Hope, November 1855.
He is the author of the Hymn text, "O thou who makest souls to shine" which appears in some of the editions of Hymns Ancient and Modern.