As in, what comes to mind when you think of evil? What do you consider to be the ultimate evil thing, be it person, act, organization, etc.
Personally, when I think of evil, I generally think of the Borg from Star Trek. While most villains I see have some kind of compassionate side, the Borg do not. They exist solely to assimilate the entire universe, and don't give a damn about identity or self-determination. They are cold, cruel, calculating, and above all, ruthless.
What about you guys?