Duncan (pop. 4,812) is a city in southern Vancouver Island, British Columbia, Canada. It is about 50 kilometres from both Victoria in the south and Nanaimo in the north. It has a population of just 4,812 however; it serves the Cowichan Valley, which has a total population of 77,561. Before the U.S.-Canada softwood lumber dispute Duncan and the whole Cowichan Valley was a thriving lumber centre in British Columbia. It is the seat of the Cowichan Valley Regional District.

Duncan's tourisim slogan is "The City of Totems"; the city has many totem poles around the downtown area, which were erected in the late 1980's. A local nickname for the city is Drunken Duncan, due to the stereotype of Duncan being a heavy consumer of beer, most notably Lucky Beer . It is also the home of the "World's Largest Hockey Stick", which was at Expo 86 in Vancouver.

Duncan is home to a very large First Nations community, and traditional home of the Coast Salish Indians; they are the largest band in the Coast Salish tribe. The Salish are makers of the world famous Cowichan Sweaters .