Plains Indians or Indigenous peoples of the Great Plains and Canadian Prairies are the Native American tribes and First Nation band governments who have historically lived on the Interior Plains of North America. While hunting-farming cultures have lived on the Great Plains for centuries prior to European contact, the region is known for the horse cultures that flourished from the 17th century through the late 19th century. Their historic nomadism and armed resistance to domination by the government and military forces of Canada and the United States have made the Plains Indian culture groups an archetype in literature and art for Native Americans everywhere.

The Great Plains, sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located just to the east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. It is the western part of the Interior Plains, which also include the mixed grass prairie, the tallgrass prairie between the Great Lakes and Appalachian Plateau, and the Taiga Plains and Boreal Plains ecozones in Northern Canada. Great Plains or Western Plains is also used to describe the ecoregion of the Great Plains, or alternatively the western portion of the Great Plains.