There are lots of words to describe poor southern white people, that are not intended to apply to all white people: Cracker, Peckerwood, Redneck, Hillbilly etc. These are really class designations, rather than purely racial ones. And of course these terms are deliberately abusive, but they just don't have the history to be as destructive as the slurs used against black people. Of course, that's easy for me to say, as I am neither poor nor southern.

The only terms I can think of that apply to all white people are Honky and Ofay. I've seen them used by some black people to refer to white people, usually when talking about racism in general.