William John Patterson (May 13, 1886 – June 10, 1976) was a Liberal politician and Premier of Saskatchewan, Canada. He was first elected to the Legislative Assembly of Saskatchewan in the 1921 election. He succeeded James G. Gardiner to become the province's first Saskatchewan-born premier in 1935.
Patterson's leadership was considered to be uninspired. He was unable to resist the Co-operative Commonwealth Federation's rise to power in the 1944 election under Tommy Douglas. Patterson's Liberals were reduced to five seats in the Legislature. He resigned as Liberal leader in 1946.
Patterson served as the tenth Lieutenant Governor of Saskatchewan from 1951 to 1958, becoming the first person to have been both Premier and lieutenant governor of the province.
Paterson was born on May 13, 1886, in Grenfell in what was then the District of Assiniboia of the North-West Territories. His father, John Patterson, had moved to Grenfell in 1882 to work as a railway section foreman during the construction of the Canadian Pacific Railway. His mother, Catherine Fraser, was an immigrant from Scotland.
Patterson left school at 15 and found work first at a bank and then in the Saskatchewan Department of Telephones. Following the outbreak of World War I, Patterson in 1916 enlisted in the Canadian Army, serving as a cavalry officer. He was wounded in September 1918.