John O'Connor PC (January 1, 1824 – November 3, 1887) was a Canadian politician and cabinet minister. Born in Boston, Massachusetts, the son of Irish immigrants John and Mary O’Connor, he moved with his family to Essex County, Upper Canada in 1828. He was re-elected again in the 1878 federal election for the riding of Russell. From 1878 to 1880, he again was the President of the Privy Council. As well he was the Postmaster General in 1880 and from 1881 to 1882. From 1880 to 1881, he was the Secretary of State of Canada. In 1884, he was appointed a judge of the Court of Queen’s Bench for Ontario.