The Blackfoot Confederacy, Niitsitapi, or Siksikaitsitapi, is a historic collective name for linguistically related groups that make up the Blackfoot or Blackfeet people: the Siksika ("Blackfoot"), the Kainai or Blood, and two sections of the Peigan or Piikani – the Northern Piikani (Aapátohsipikáni) and the Southern Piikani. Broader definitions include groups such as the Tsúùtínà (Sarcee) and A'aninin who spoke quite different languages but allied with or joined the Blackfoot Confederacy.

The Siksika Nation is a First Nation in southern Alberta, Canada. The name Siksiká comes from the Blackfoot words sik (black) and iká (foot), with a connector s between the two words. The plural form of Siksiká is Siksikáwa. The Siksikáwa are the northernmost of the Niitsítapi, all of whom speak dialects of Blackfoot, an Algonquian language.