William John Patterson (May 13, 1886-June 10, 1976) was a Liberal 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 lieutenant-governor of the province from 1951 to 1958, becoming the first person to have been both Premier and lieutenant-governor of the province.