The Opposition House Leader (), officially known as leader of the Official Opposition in the House of Commons of Canada, is a member of the Official Opposition, not to be confused with the Leader of the Official Opposition, but is generally a senior member of the frontbench. The House Leader is responsible for questioning the Government House Leader on the forthcoming business of the House of Commons, negotiating with the Government House Leader and other parties' house leaders on the progress of business in the House, and managing the Official Opposition's business in the House of Commons.
The position of Opposition House Leader evolved in the 1950s as each Opposition party began to designate a particular MP to question the Government House Leader on upcoming House business. The title of Opposition House Leader became official in 1963, and in 1974, a special annual indemnity was attached to the position of House Leader in each of the opposition parties. The House Leader also coordinates the Official Opposition's floor strategy, often with the House leaders of smaller opposition parties. The position is particularly important when there is a minority government, or a government with a slim majority, which may be defeated by a vote of no confidence if all opposition parties work together.
Notable Opposition House leaders include Herb Gray of the Liberal Party (also a Government House Leader) and Erik Nielsen of the Progressive Conservative Party.
Notable House leaders of other recognized parties include New Democratic Party MPs Stanley Knowles, who was the House Leader for the NDP from 1962 to 1981, and Bill Blaikie, who held the same position from 1996 until 2003.