John Thomas Emmett was an English architect and designer based in London.
He was born on 18 August 1823, the son of John Emmett and Mary Saunders.
By 1846 he was working in practice at 11 Beaufort Buildings in London. By 1868 he was at 1 Cloudesley Square, Islington in London. In 1857 he was declared bankrupt., but by 1865 was a director of the North London, Highgate and Alexandra Park Railway.
He was a devotee of the Gothic style of architecture, and unafraid to criticise his colleagues building in more contemporary styles.
In 1872 he published an article in the Quarterly Review on ‘The state of English architecture’ which drew attacks from other architects.