William Sinclair (b. c. 1794 – 12 October 1868) was a chief factor of the Hudson's Bay Company.
Weather forced them to winter in James Bay and his resourcefulness in these trying circumstances furthered his career.
The trek was to the forks of the South Saskatchewan and Red Deer rivers.
He added an 850-mile side trip on this occasion, along with John Edward Harriott, to the Cypress Hills and Missouri country.
William Sinclair's career became increasingly filled with important tasks and he was regarded as a valued officer of the Hudson's Bay Company.