Ohiyesa

Charles Eastman, or "Ohiyesa"
  in Santee, came of age during a period of increasing tension and violence between
  Native and "new" Americans. Raised to become a hunter-warrior, he
  was nevertheless persuaded by his Christianized father to enter the alien world
  of white society. A remarkably bright student, Eastman graduated from Dartmouth
  College and the Boston University School of Medicine. Later on he served as
  government physician at the Pine Ridge Agency (and tended casualties at Wounded
  Knee), as Indian Inspector for the Bureau of Indian Affairs, and as Indian secretary
  for the YMCA, and helped found the Boy Scouts of America.
Concurrently, however, he also worked
  on special congressional legislation to settle Sioux claims and was a charter
  member and later president of the Society of American Indians. It was his writing,
  though, which most clearly established Eastman's determination to hold on to
  his roots. In works such as Indian Boyhood, The Soul of the Indian, and
  Indian Heroes and Chieftains he reconfirmed his native heritage and tried
  to make white society aware of the Indians' contribution to American civilization.