In a competitive world with limited resources, our desire system never rests. This is a good thing as it motivates us to take care of our self-interests and strive for bigger and better. But a desire system that never sleeps is a system that is motivated to accrue ever larger coffers or power. To satisfy this inflationary need is often not possible without harming others, either directly or indirectly. To offset the costs of harming another, desire recruits denial. This is a recipe for evil and the creation of excessive harms. It is a recipe that takes two, often benign and highly adaptive ingredients that are essential for motivating action and promoting survival, and combines them into an explosive outcome. Seen in this way, our capacity for evil is as great as our capacity for love and compassion. Evil is part of human nature, a capacity that can’t be denied. What I will show is both how this capacity works, and how some of us, due to biological inheritance and environmental influence, are more likely to end up as evildoers. Historical material on the lives of Franz Stangl and Adolf Eichmann, leaders in the Nazi annihilation of Jews, illustrates how desire and denial combine within individual minds to create excessive harms. Although this is a historical example, focused on the lives of only two men, stories like theirs have been recounted hundreds of times, all over the globe and across time. This pattern points to common mechanisms, identified in detail by the sciences of human nature. Stangl was a politically motivated man with a burning desire to climb to the top of the Nazi hierarchy. A clear path opened when he was appointed commander of the Polish prison Treblinka. Unbeknownst to Stangl, Treblinka was one of the Nazi’s concentration death camps. To fulfill his desire for power therefore required harming thousands of others, or more accurately, commanding Nazi soldiers to harm others on his behalf. But since Stangl had no burning desire to harm the Jews,