David Lewis (June 23, 1909-May 23, 1981) was a Russian-born Canadian labour lawyer and politician. He was national secretary of the Cooperative Commonwealth Federation from 1936 to 1950, and, with Stanley Knowles, was one of the key architects of the NDP in 1961.

Lewis was born in the town of Svisloch in Russia to a Jewish family active in the Bund. He and his family emigrated to Montreal in 1921 where he grew up and attended McGill University. He won a Rhodes Scholarship and went to study at Oxford University where he became president of the Oxford Union. He was active in the British Labour Party and was offered a safe seat in the British House of Commons but declined and returned to Canada to practice law.

An active member of the Cooperative Commonwealth Federation, Lewis became the party's national secretary in 1936 and was for many years the party's sole paid employee. He ran for the Canadian House of Commons in 1940, 1943, 1945 and 1949 but was defeated on each occasion (in the case of the 1943 by-election in Cartier, Quebec he lost to Fred Rose who became Canada's first and only MP for the Communist Party of Canada). Lewis resigned as national secretary in 1950 and moved to Toronto to practice law in partnership with Ted Jolliffe. He became the chief legal advisor to the United Steel Workers of America's Canadian division and assisted them in their organising efforts and in their battles with the Communist led Mine, Mill union.

Lewis was elected as a Member of Parliament from 1962 to 1963 and 1965 to 1974 establishing himself as one of the leading debaters in the House of Commons. In 1971 he ran to succeed retiring NDP leader Tommy Douglas and won the NDP leadership convention. He led the NDP thru the 1972 Canadian election in which he uttered his best known quotation calling Canadian corporations "corporate welfare bums". That election campaign returned a minority government and elected the greatest number of NDP MPs until 1988, and left the NDP holding the balance of power until 1974. Lewis and the NDP propped up the Liberal government of Pierre Trudeau in exchange for the implementation of NDP proposals such as the creation of Petro-Canada as a crown corporation. In the 1974 Canadian election, however, Lewis lost his seat and leading him to resign as party leader. In 1976 he was made a Companion of the Order of Canada.

David Lewis died in 1980. He is the father of Stephen Lewis, a former Ontario New Democratic Party leader who is now the United Nations Special Envoy for HIV/AIDS in Africa.

Broadcaster Avi Lewis is David Lewis' grandson (and the son of Stephen).

Preceded by: Tommy Douglas

NDP leaders

Succeeded by: Ed Broadbent