Moral evil is the result of any morally negative event caused by the intentional action or inaction of an agent, such as a person. An example of a moral evil might be murder, or any other evil event for which someone can be held responsible or culpable.

This concept can be contrasted with Natural evil in which a bad event occurs without the intervention of an agent. The dividing line between natural and moral evil is not absolutely clear however as some behaviour can be unintentional yet morally significant and some natural events, for example; global warming can be caused by intentional actions.