Vine Deloria Jr. (1933–2005) was an American author, theologian, historian, and activist. He was a prominent figure in the American Indian Movement of the 1960s and 1970s and was a key figure in the development of the field of Native American studies. He wrote a number of influential books on Native American history and culture, including Custer Died for Your Sins: An Indian Manifesto (1969) and God Is Red (1973).