The Duwamish (Lushootseed: dxʷdəwʔabš, [dxʷdəwʔɑbʃ]) are a Lushootseed-speaking Southern Coast Salish people in western Washington, and the Indigenous people of metropolitan Seattle.

Prior to colonization, the center of Duwamish society was around the Black and Duwamish rivers in Washington. The modern Duwamish primarily descend from two separate groups: the dxʷdəwʔabš, or Duwamish, and the x̌ačuʔabš, a group of peoples whose traditional territory extends around Lake Washington. Although the primary language used by the Duwamish today is English, the Duwamish historically spoke a subdialect of the southern dialect of Lushootseed, a Coast Salish language spoken throughout much of western Washington.

For centuries, the Duwamish have lived in at least 17 villages around the Seattle area. In 1855, the Duwamish were among the signatories of the 1855 Treaty of Point Elliott, in which they ceded their land to the United States government and in return would remove to reservation lands established by the treaty. Two reservations were created for the Duwamish: the Muckleshoot and Suquamish reservations. However, no reservation was ever created directly in the Duwamish homeland. Since then, although many Duwamish did move to the reservations, many others did not, preferring to remain in their homelands, creating a schism between Duwamish descendants. Today, the Duwamish, including the modern tribes descended from the aboriginal Duwamish such as the Suquamish Nation, the Muckleshoot Indian Tribe, and the unrecognized Duwamish Tribe, have been a large part of the modern history of the Seattle area, continuing to advocate for their treaty rights and the preservation and revitalization of their culture, language, and land.

Duwamish people today are enrolled in several different tribes. These include the unrecognized Duwamish Tribe and the federally recognized tribes:

The name "Duwamish" is an anglicization of the Lushootseed name dxʷdəwʔabš. The name dxʷdəwʔabš means "people inside the bay." The name refers to the Cedar River, which is called dxʷdəw in Lushootseed, and means "inside the bay." The name references the way the Duwamish villages were located inland, rather than along Puget Sound.

The name is composed of the prefix dxʷ-, meaning "toward, to," the suffix =abš, meaning "people," and the root word √dəw, a variant form of dəkʷ, meaning "inside something relatively small." dxʷdəwʔabš has also been spelled variantly as dxʷduʔabš.

The Duwamish are a Southern Coast Salish people. The Southern Coast Salish are a group of related peoples who share similar culture, history, and customs. Included in this classification are the many Lushootseed-speaking peoples and the Twana (who speak the Twana language). The broader Coast Salish are a group of related peoples who have elements of shared history and culture and speak related languages.

Prior to colonization, "Duwamish" (dxʷdəwʔabš) originally referred to just those from Elliott Bay and the Duwamish, Black, and Cedar Rivers. However, beginning around 1855, the word "Duwamish" was used to also include the Green and White river peoples and the x̌ačuʔabš. The x̌ačuʔabš were composed of several related peoples whose villages were located along Lake Washington and the Sammamish River; the x̌aʔx̌ačuʔabš, whose villages were located around Lake Union, and the Shilshole (šilšulabš), whose village was located on Salmon Bay. At the time of initial major European contact, these peoples considered themselves wholly distinct from the Duwamish.