Inflicting pain and/or suffering on another human being solely to satisfy some selfish gain.
EDIT: That gain could be money, or pleasure, or just the desire "to watch the world burn" as many have pointed out. The point is, true evil makes others suffer in order to satisfy its own desires, however logical or chaotic they may be.
Rape, murder*, taking enjoyment out of someone else's suffering**, these would all fall under that umbrella.
*By murder, I don't include killing in self defense, or killing in a war situation, or this...
Angerwing said:
Murder can be justified. If I had a child, and someone molested/killed them, I would murder the guy. Legally wrong, but I would personally find that morally acceptable.
...which I wouldn't even call "murder," I'd call it "natural justice." Then again, I tend to agree with Frank Castle on this point: "In some extreme situations, the law is inadequate. In order to shame its inadequacy, it becomes necessary to act outside the law, to pursue natural justice."
(And now I've just been added to an FBI watch list...)
**I'm not talking about laughing at the guys from Jackass or laughing at your friend because he tripped and fell or laughing at the melodramatic emo teenager. I'm talking about TRUE suffering: people who are genuinely starving/hurting/grieving/dying.
Ungh, I hate semantics.