William John Duncan Dempster was a member of the North-West Mounted Police (NWMP) in the Yukon Territory during the early 20th century. He gained notice for his involvement in finding the Lost Patrol, three NWMP officers and an ex-NWMP officer/guide who disappeared on the trail between Fort McPherson and Dawson City in the winter of 1910–11. The Dempster Highway in northern Canada is named for him.

The Dempster Highway, also referred to as Yukon Highway 5 and Northwest Territories Highway 8, is a highway in Canada that connects the Klondike Highway in Yukon to Inuvik, Northwest Territories on the Mackenzie River delta. The highway crosses the Peel and the Mackenzie rivers using a combination of seasonal ferry services and ice bridges. Year-round road access from Inuvik to Tuktoyaktuk opened in November 2017, with the completion of the Inuvik–Tuktoyaktuk Highway, creating the first all-weather road route connecting the Canadian road network with the Arctic Ocean.