William John Patterson (May 13, 1886 – June 10, 1976) was a Liberal politician and the sixth premier of Saskatchewan from 1935 to 1944.

He was unable to resist the Co-operative Commonwealth Federation's rise to power in the 1944 election under Tommy Douglas.

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.

Neff and then moved to Windthorst, Saskatchewan to set up a financial and insurance agency.

[1] Patterson held several cabinet positions in governments headed by Premier James Garfield Gardiner.

Taking office in the midst of the Great Depression, Patterson sought to extend social programs to assist those in need.

However, Patterson subscribed to the conventional wisdom of the day that deficit spending would ruin the province's credit and he thus therefore refused to run a budget deficit, instead funding the increased government spending through a new sales tax.

In the 1944 election, however, the Liberals were easily defeated by the Saskatchewan Co-operative Commonwealth Federation, under the leadership of Tommy Douglas.

The Co-operative Commonwealth Federation under George Hara Williams came in second place and continued as the Official Opposition.

Patterson again led the Liberals in the general election of 1944, but this time was soundly defeated by Tommy Douglas and the Co-operative Commonwealth Federation.

Patterson stood for election to the Legislative Assembly eight times, in two different ridings, Pipestone and Cannington.

The by-election was called on Patterson accepting the position of Provincial Treasurer in the Cabinet of Premier Gardiner, an office of profit under the Crown, on February 26, 1926.