Granville Stuart (August 27, 1834 – October 2, 1918) was a pioneer, gold prospector, businessman, civic leader, vigilante, author, cattleman and diplomat who played a prominent role in the early history of Montana Territory and the state of Montana. Widely known as "Mr. Montana", Granville's life spanned the formative years of Montana from territorial times through the first 30 years of statehood. His journals and writings have provided Montana and western historians unique insights into life in the Northern Rockies during the second half the 19th century.