Little Big Man (1964)

Little Big Man is a 1964 novel by American author Thomas Berger. Often described as a satire or parody of the western genre, the book is a modern example of picaresque fiction. Berger made use of a large volume of overlooked first-person primary materials, such as diaries, letters, and memoirs, to fashion a wide-ranging and entertaining tale that comments on alienation, identity, and perceptions of reality.

see also the book by Dee Brown (1970)