Major General Sir John Terence Nicholls O'Brien CMG (23 April 1830 – 25 February 1903) was a surveyor, engineer and colonial governor. Born in Manchester, England, O'Brien studied at Elizabeth College, Guernsey, and then attended the Royal Military College, Sandhurst. O'Brien, a British Army officer, received a medal of honour for his service in the Indian Mutiny War. He was appointed acting Governor of British Ceylon in 1863 and held the office for two years, succeeding Charles Justin MacCarthy. O'Brien died in 1903 in London, England.