Great Slave Lake is the second-largest lake in the Northwest Territories, Canada (after Great Bear Lake), the deepest lake in North America at 614 m (2,014 ft), and the tenth-largest lake in the world by area. It is 469 km (291 mi) long and 20 to 203 km (12 to 126 mi) wide. It covers an area of 27,200 km² (10,500 sq mi) in the southern part of the territory. Its given volume ranges from 1,070 km³ (260 cu mi) to 1,580 km³ (380 cu mi) and up to 2,088 km³ (501 cu mi) making it the 13th largest by volume.

The lake shares its name with the First Nations peoples of the Dene family called Slavey by their enemies the Cree. Towns situated on the lake include (clockwise from east) Łutselk'e, Fort Resolution, Hay River, Hay River Reserve, Behchokǫ̀, Yellowknife, Ndilǫ, and Dettah. The only community in the East Arm is Łutselk'e, a hamlet of about 350 people, largely Chipewyan Indigenous peoples of the Dene Nation, and the abandoned winter camp and Hudson's Bay Company post Fort Reliance. Along the south shore, east of Hay River is the abandoned Pine Point Mine and the company town of Pine Point.

Indigenous peoples were the first settlers around the lake after the retreat of glacial ice. Archaeological evidence has revealed several different periods of cultural history, including the Northern Plano tradition (8,000 years before present), Shield Archaic tradition (6,500 years), Arctic small tool tradition (3,500 years), and the Taltheilei Shale tradition (2,500 years before present). Each culture has left a distinct mark in the archaeological record based on type or size of lithic tools.

Great Slave Lake was put on European maps during the emergence of the fur trade towards the northwest from Hudson Bay in the mid 18th century. The name 'Great Slave' came from the English-language translation of the Cree exonym, Awokanek (Slavey), which they called the Dene Tha. The Slavey people were Dene tribes living on the lake's southern shores at that time. As the French explorers dealt directly with the Cree traders, the large lake was referred to as "Grand lac des Esclaves" which was eventually translated into English as "Great Slave Lake".

In the 1930s, gold was discovered on the North Arm of Great Slave Lake. This discovery led to the establishment of Yellowknife, which would become the capital of the NWT. In 1960, an all-season highway was built around the west side of the lake; the highway was originally an extension of the Mackenzie Highway, but became known as Yellowknife Highway or Highway 3.^{[citation needed]}

On 24 January 1978, a Soviet Radar Ocean Reconnaissance Satellite named Kosmos 954, which contained an onboard nuclear reactor, fell from orbit and disintegrated. Pieces of the nuclear core fell in the vicinity of Great Slave Lake. Some of the nuclear debris was recovered by a joint Canadian Armed Forces and United States Armed Forces military operation called Operation Morning Light.

In the late 2010s, many placenames within the Northwest Territories were restored to their indigenous names. It has been suggested--particularly because of the mention of slavery--that the lake be renamed as well. "Great Slave Lake is actually a very terrible name, unless you're a proponent of slavery," says Dëneze Nakehk'o, a Northwest Territories educator and founding member of First Nations organization Dene Nahjo. "It's a beautiful place. It's majestic; it's huge. And I don't really think the current name on the map is fitting for that place." He has suggested Tu Nedhé, the Dene Soline name for the lake, as an alternative. Tucho, the Dehcho Dene term for the lake, has also been suggested.

The Hay, Slave (which in turn includes the Peace), Lockhart, and Taltson Rivers are its chief tributaries. It is drained by the Mackenzie River. Though the western shore is forested, the east shore and northern arm are tundra-like. The southern and eastern shores reach the edge of the Canadian Shield. Along with other lakes such as the Great Bear and Athabasca, it is a remnant of the vast glacial Lake McConnell.