Hon. Stanley Howard Knowles (June 18, 1908 - June 9, 1997) was a Canadian parliamentarian. Knowles represented the riding of Winnipeg North Centre from 1942 to 1958 on behalf of the Cooperative Commonwealth Federation and again from 1962 to 1984 representing the CCF's successor, the New Democratic Party.

Knowles was widely regarded and respected as the foremost expert on parliamentary procedure in Canada and served as the CCF and NDP House Leader for decades. He was also a leading advocate of social justice and was largely responsible for persuading the governments to increase Old Age Security benefits and for the introduction of the Canada Pension Plan as well as other features of the welfare state.

Knowles was brought up in the social gospel movement and became a United Church minister. He joined the CCF in 1935 during the Great Depression and (after a failed bid for the Manitoba legislature in 1941) was first elected to the House of Commons in a 1942 by-election in Winnipeg North Centre held on the death of former CCF leader J. S. Woodsworth. He became an expert on parliamentary procedure and used his skills to humiliate the Liberal government of Louis St. Laurent during the 1956 pipeline debate which helped contribute to the government's electoral defeat in the 1957 Canadian election.

John George Diefenbaker was so impressed by Knowles' skill that when he became Prime Minister as a result of that election he asked Knowles to become Speaker of the Canadian House of Commons; Knowles declined.

He lost his seat in the 1958 Canadian election that almost wiped out the CCF and went to work for the Canadian Labour Congress. He and David Lewis came up with a strategy to create a new party that would bring the old CCF together with the labour movement by partnering the party with the CLC. This new party was launched as the New Democratic Party of Canada in 1961. Knowles returned to parliament as an MP for the new party as a result of the 1962 Canadian election and played a crucial role through minority governments of the 1960s and 1970s using the NDP's position holding the balance of power to persuade successive Liberal governments to introduce progressive measures.

In 1979 he became a member of the Queens Privy Council.

Knowles battled multiple sclerosis since 1946 but it was his 1981 stroke that ultimately removed him from public life. He retired from politics in 1984 but was given the unprecedented distinction of being made an honourary table officer of the House of Commons by Prime Minister Pierre Trudeau. This allowed him to spend his retirement viewing parliamentary debates from the floor of the House and he was often seen to do so until further strokes left him bed-ridden.

In 1984 he was made an Officer of the Order of Canada.