Athabaskan (/ˌæθəˈbæskən/ ATH-ə-BASK-ən; also spelled Athabascan, Athapaskan or Athapascan), also known as Dene (/ˈdeɪneɪ/ DAY-nay; also spelled Dené), is a large branch of the Na-Dene language family of North America, located in western North America in three areal language groups: Northern, Pacific Coast and Southern (or Apachean). Kari and Potter (2010:10) place the total territory of the 53 Athabaskan languages at 4,022,000 square kilometres (1,553,000 sq mi).

Chipewyan is spoken over the largest area of any North American native language, while Navajo is spoken by the largest number of people of any native language north of Mexico.

The word Athabaskan is an anglicized version of a Cree language name for Lake Athabasca (Moose Cree: Āðapāskāw '[where] there are reeds one after another') in Canada. Cree is one of the Algonquian languages and therefore not itself an Athabaskan language. The name was assigned by Albert Gallatin in his 1836 (written 1826) classification of the languages of North America. He acknowledged that it was his choice to use this name for the language family and the associated ethnic groups: "I have designated them by the arbitrary denomination of Athabascas, which derived from the original name of the lake."^{[full citation needed]}

The four spellings—Athabaskan, Athabascan, Athapaskan, and Athapascan—are in approximately equal use. Particular communities may prefer one spelling over another (Krauss 1987). For example, the Tanana Chiefs Conference and Alaska Native Language Center prefer the spelling Athabascan. Ethnologue uses Athapaskan in naming the language family and individual languages.

Although the term Athabaskan is prevalent in linguistics and anthropology, there is an increasing trend among scholars to use the terms Dené and Dené languages, which is how many of their native speakers identify it. They are applying these terms to the entire language family. For example, following a motion by attendees in 2012, the annual Athabaskan Languages Conference changed its name to the Dené Languages Conference.

Linguists conventionally divide the Athabaskan family into three groups, based on geographic distribution:

The 38 Northern Athabaskan languages are spoken throughout the interior of Alaska and the interior of northwestern Canada in the Yukon and Northwest Territories, as well as in the provinces of British Columbia, Alberta, Saskatchewan and Manitoba. Five Athabaskan languages are official languages in the Northwest Territories, including Chipewyan (Dënesųłıné), Dogrib or Tłı̨chǫ Yatıì, Gwich'in (Kutchin, Loucheux), and the Northern and Southern variants of Slavey.

The seven or more Pacific Coast Athabaskan languages are spoken in the Pacific Northwest of the United States. These include Applegate, Galice, several Rogue River area languages, Upper Coquille, Tolowa, and Upper Umpqua in Oregon; Eel River, Hupa, Mattole–Bear River, and Tolowa in northern California; and possibly Kwalhioqua-Clatskanie in Washington.