William Melville Martin (August 23, 1876-June 22, 1970) served as Liberal Premier of the Canadian province of Saskatchewan from 1916 to 1922.

Martin was elected to the House of Commons for Regina in the Canadian federal election, 1908 federal election, and re-elected in the 1911 election. In 1916, he entered provincial politics to take over the leadership of the Saskatchewan Liberal Party and become Premier. Martin, an outsider to provincial politics, was chosen by the Liberals in order to help distance them from allegations of corruption. Martin brought farmers' advocate Charles A. Dunning into the cabinet in an attempt to revitalise the Liberals, and instituted reforms to clean up the government. These changes were successful in cleansing the government's image, and Martin led the government to re-election in the 1917 election, winning 51 of 55 seats.

The United Farmers and Progressive movements were riding a national wave of agrarian discontent which undercut the Liberals across Canada, and threatened to engulf the Saskatchewn Liberals as well. Martin successfully countered the populist movement, and brought it into the Liberal party by bringing in Dunning and also by recruiting another farm leader, J.A. Maharg, into the government. The Liberals were able to resist the Progressive challenge in the 1921 election, which returned 46 Liberals to 6 Progressives, 7 Independents, 1 Labour MLA and 3 Conservatives.

Martin retired from politics in 1922 and became a judge of the Saskatchewan Court of Appeal. From 1941 until 1961, Martin was chief justice of the Supreme Court of Saskatchewan.