Sir John Richard Quain (1816–1876) was an Irish barrister and judge in England.
After reading in the chambers of Thomas Chitty, and practising as a special pleader for a time, he was called to the bar at the Middle Temple on 30 May 1851.
In 1866 he became a Queen's Counsel, and in 1867 was made Attorney-General for the county palatine of Durham and a bencher of the Middle Temple.
His health failed early in 1876, and, after some months of intermittent illness, he died at his house, 32 Cavendish Square, London, on 12 September and was buried at Finchley.
His law library was presented to University College, London, by his brother Richard in 1876.