Sir James Pliny Whitney (October 2, 1843-September 25, 1914) was a politician in the Canadian province of Ontario. Whitney was a lawyer in eastern Ontario, Conservative member for Dundas from 1888 to 1914, and Premier of Ontario from 1905 to 1914.

Whitney became leader of the party in 1896 taking it from a narrow, bigoted rump into a forward-looking party determined to build the province. In the 1905 election, he led the Tories to victory for the first time in 33 years by defeating the Liberal government of George William Ross.

Whitney's government laid the basis for Ontario's industrial development by creating the Hydro-Electric Power Commission of Ontario, with Sir Adam Beck as its chairman and driving force. His government also passed the Workmen's Compensation Act and enacted temperance legislation. He also appeased the anti-Catholic, anti-French-Canadian sentiments of supporters of the Orange Order in his caucus (such as George Howard Ferguson) by passing Regulation 17. This regulation banned the teaching of French in schools beyond the first three years of school. The measure inflamed French-Canadian opinion across Canada, particularly in Quebec, and split the country as it entered World War I.

Whitney died in office shortly after winning the 1914 election.