William Thomas Hamilton (1822 - 1908), also known as Wildcat Bill, was a mountain man, trapper, and scout of the American West. Some accounts say he was "Scottish born", others that he was in the River Till area of Northumberland. He and his parents emigrated to the USA from Scotland while he was an infant.

Trapping from an early age, in the 1850s he became an Indian fighter and at the end of the decade established a trading post, concurrently holding a variety of jobs including county sheriff.