The Northwest Territories (abbreviated NT or NWT; French: Territoires du Nord-Ouest, formerly North-Western Territory and North-West Territories and namely shortened as Northwest Territory) is a federal territory of Canada. At a land area of approximately 1,144,000 km² (442,000 sq mi) and a 2016 census population of 41,790, it is the second-largest and the most populous of the three territories in Northern Canada. Its estimated population as of 2022 is 45,605. Yellowknife is the capital, most populous community, and only city in the territory; its population was 19,569 as of the 2016 census. It became the territorial capital in 1967, following recommendations by the Carrothers Commission.

The Northwest Territories, a portion of the old North-Western Territory, entered the Canadian Confederation on July 15, 1870. Since then, the territory has been divided four times to create new provinces and territories or enlarge existing ones. Its current borders date from April 1, 1999, when the territory's size was decreased again by the creation of a new territory of Nunavut to the east, through the Nunavut Act and the Nunavut Land Claims Agreement. While Nunavut is mostly Arctic tundra, the Northwest Territories has a slightly warmer climate and is both boreal forest (taiga) and tundra, and its most northern regions form part of the Arctic Archipelago.

The Northwest Territories has the most interprovincial and inter-territorial land borders among all provinces and territories of Canada. It is bordered by the territories of Nunavut to the east and Yukon to the west, and by the provinces of British Columbia, Alberta, and Saskatchewan to the south; it also touches Manitoba to the southeast at a quadripoint that includes Nunavut and Saskatchewan. The land area of the Northwest Territories is vast enough to be roughly equal to France, Portugal and Spain combined, although its overall area is even larger because of its vast lakes that freeze over in winter.