The Collaborative International Dictionary of English v.0.48:

darky \dark"y\, n.
   a negro; an African-American; -- an older term now considered
   offensive. [Slang]

   Syn: darkie, darkey.
        [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

darky
    n 1: (ethnic slur) offensive term for Black people [syn:
         darky, darkie, darkey]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "darky":
   American Indian, Amerind, Australian aborigine, Bushman, Caucasian,
   Indian, Malayan, Mister Charley, Mongolian, Negrillo, Negrito,
   Negro, Oriental, Red Indian, WASP, black, black man, blackfellow,
   boy, brown man, burrhead, colored person, coon, gook, honky,
   jigaboo, jungle bunny, nigger, niggra, ofay, paleface, pygmy,
   red man, redskin, slant-eye, spade, the Man, white, white man,
   whitey, yellow man