I do. I've only met one person who was evil and he was bloody scary. I've talked about him on here bef ore. He was a kid at school and my dad taught him before I met him, he was the only one of whom my dad ever said "I'll tell you this straight, *do not* have anything to do with him. I wouldn't say this about any other kid but JC is warped. He's a criminal." He was. Last I heard he had done time for drug dealing. I'm not afraid of anyone or anything, and I've worked with slaughter men in abattoirs where you take a deep breath before talking to them, no problem, but I was afraid of him. My dad said that as a teacher he dealt with every kid in the school, and this lad, aged 13, actually scared him, as an adult.
But in terms of who could harm or kill others, the answer is unfortunately "all of us." Was it the Stamford experiment where they set up a prison? I think it's the great flaw of our species, our ability to form tribes allows us to cooperate within the tribe but allows us to think that any atrocity we like is acceptable when it's directed at "those other bastards from the other side of the river".