There is apparently some sort of email claim circulating that "democrats" started the KKK after the civil war, which while this is technically true in that those that founded it would have been (at that time) affiliated with the Democratic party, it doesn't actually translate very well to the current party's platform. Many of those "southern democrats" later became affiliated with the Republican party.
Yes it was a white Southern Democrats and started the clan not only did they go after blacks but they went after Jews and Catholics and Republicans. Anyone who was not like them thought like them they went after. The men who started the clan fought for the South during the Civil War.
It was 6 Confederate Civil War veterans about a year after the war ended. At first it was called the Ku Klos Klan from the Greek word Kuklos meaning circle no beginning or an end and they took the Scottish word Clan and replaced the C with a K so it would go with the flow so at first it was called the Ku Klos Klan then they corrupted in I believe the late 1890's or early 1900's then after a movie called "A Nation Reborn" I believe that's what it was called made by D.W. Griffith and it inspired a man to start the 2nd Klan much bigger than the original the cross lightings didn't appear until the late 1920's and in the mid 1960's they fell apart. Nowadays there are separate Klans there isn't even an actual Klan anymore their nothing but small groups divided and refuse to work with other Klans because each one believes that their Klan they made up is more powerful than this one or that one so honestly their nothing to worry about nowadays considering they don't do anything anymore.