The Selk'nam genocide was the systematic extermination of the Selk'nam people, one of the four indigenous peoples of Tierra del Fuego, in the late 19th and early 20th centuries. Historians estimate that the genocide spanned a period of between ten and twenty years, and resulted in the decline of the Selk'nam population from approximately 4,000 people during the 1880s to a few hundred by the early 1900s.

The Selk'nam, also known as the Onawo or Ona people, are an indigenous people in the Patagonian region of southern Argentina and Chile, including the Tierra del Fuego islands. They were one of the last native groups in South America to be encountered by migrant Europeans in the late 19th century. In the mid-19th century, there were about 4,000 Selk'nam; in 1916 Charles W. Furlong estimated there were about 800 Selk'nam living in Tierra del Fuego; with Walter Gardini stating that by 1919 there were 279, and by 1930 just over 100.