Blackface

"The stock characters of blackface minstrelsy have played a significant role in disseminating racist images, attitudes and perceptions worldwide. Every immigrant group was stereotyped on the music hall stage during the 19th Century, but the history of prejudice, hostility, and ignorance towards black people has insured a unique longevity to the stereotypes. White America's conceptions of Black entertainers were shaped by minstrelsy's mocking caricatures and for over one hundred years the belief that Blacks were racially and socially inferior was fostered by legions of both white and black performers in blackface."
--http://black-face.com