In lots of American Indian novels you can read that the native peoples of North America called European people "pale-face" or "pale-faced":
“Young Randolph! war-chief among the pale-faces! You have not then forgotten poor Haj-Ewa?” (Osceola the Seminole, Thomas Mayne Reid)
"Poor Injin dat, b'lieve. Why come so late?—why no come when 'e foot of Susquesus light as feather of bird?—why stay away till pale-faces plentier dan leaf on tree, or snow in air? Hundred year ago, when dat oak little, sich Injin might be good; now, he good for nuttin'." (The Redskins, James Fenimore Cooper)
Welcome, my paleface brother, what good news brings you here? (Songs of the Prairie, Robert J. C. Stead)
Is it just a literary device invented by the authors of European descent, or that racial slur was actually used by some Native American tribes?