Robert Byrd, A Senator from Kentucky who was also the "Exalted Cyclops" of the KKK. Hillary called him her "mentor".
As far as racist, though not a member of the KKK, Joe Biden has been openly racist throughout his career,
Then there is this list, all Democrats.
https://en.wikipedia.org/wiki/Ku_Klux_Klan_members_in_United_States_politics#Robert_Byrd