The Honourable John Mercer Reid (born February 8 1937) is Information Commissioner of Canada, former president of the Canadian Nuclear Association and a former politician.

Reid was first elected to the Canadian House of Commons in the 1965 Canadian election as a Liberal Member of Parliament. In the 1968 federal election he was returned as Canada's sole Liberal-Labour MP though he remained in the Liberal caucus. The Liberal-Labour label was a reflection of a longstanding tradition in the riding of Kenora--Rainy River aimed at deflecting votes from the New Democratic Party of Canada rather than a mark of political dissent.

In 1972, Reid was redesignated as a Liberal MP and became parliamentary secretary to the President of the Queen's Privy Council for Canada and worked on issues such as improving the access of MPs to government records. In 1978, Reid joined the Canadian Cabinet of Pierre Trudeau as Minister of State for federal-provincial relations, an appointment which ended with the defeat of the Liberal government in the 1979 Canadian election. Reid remained an MP until his own personal defeat in the 1984 Canadian election.

In his post-political career Reid became a public affairs consultant. He served as president of the Canadian Nuclear Association from 1990 until 1995. He then represented Canada on the Organization for Security and Cooperation Europe 's Mission to Bosnia and Herzegovina and was also a member of the Provisional Election Commission responsible for writing and implementing an Election Act. He was also an advisor to the Chief Electoral Officer on UN Transitional Administration in Eastern Slovenia.

In 1998, Reid appointed Information Commissioner of Canada in 1998 for a seven-year term. As Information Commissioner of Canada, Reid is an independent ombudsman who investigates complaints from those who believe they have been denied rights under the Access to Information Act.