You can include American women and the suffrage movement.
A thornier question is whether "to-the-core evil" is a necessary precondition for the failure of dialogue. For example, could American slavery have been ended via dialogue, as it was in Britain, Europe, and the Northern U.S.?
I do not believe that the Southern slave-holders were "to-the-core evil," but I also do not believe that slavery would have ended without the Civil War.
Although slavery is an evil institution, the South in general, and slave-holders in particular, were clearly not all "evil to the core." They were instead unshakeable on the terms of what constituted "right and wrong" in that particular instance. In their view, it was basically a trade between their own financial well-being, and the liberty of "inferior beings."
In theory there may have been a chance -- over a course of decades or centuries -- for dialogue to work. But I doubt it. It's easy to rationalize a lot when you choose money over God.