William Warren Allmand (September 19, 1932 – December 7, 2016) was a Canadian politician who served as a Member of Parliament in the Parliament of Canada from 1965 to 1997. A member of the Liberal Party, he represented the Montreal riding of Notre-Dame-de-Grâce and served in the cabinet of Prime Minister Pierre Trudeau from 1972 to 1979. As Solicitor General, Allmand introduced legislation that successfully abolished the death penalty in Canada in 1976.

After leaving federal politics, Allmand took on the role of human rights activist, and led the International Centre for Human Rights and Democratic Development and the World Federalist Movement-Canada. He briefly returned to politics by serving a term from 2005–2009 as a Montreal city councillor under Gérald Tremblay's Union Montreal party, becoming vice president of the city council. Allmand died on December 7, 2016 from terminal brain cancer.