What makes the Emperor and Darth Vader evil?

Really, read the books and play the games buddy. The power of the dark side was fueled by hate and anger. The emperor was a xenophobic who only believe his species was superior. The empire rarely gave aliens armor as they thought it was terrible. The empire also enslaved the wookiees to build the death star and use it to rule with fear. Oh and the empire was made of the republic which was a democracy and not a dictatorship.