In, 1942, the German Reserve Police Battalion 101 assassinated 1,500 Jews in Józefów, a Polish village. Shortly before, the Battallion’s commander, Major Trapp, had assembled his men and offered: “if any of the older men among them did not feel up to the task that lay before him, he could step out” (Browning, 2001, p. 2). Only a dozen of about 500 men made use of that way out! Why not more? Why did the vast majority partake in the executions despite being offered the choice to not become mass murders? In hierarchical contexts it is typical to give orders. Yet, Trapp did not so. But he also did not ask his men whether or not they wanted to participate in the killings. He rather hit a middle-ground: He set taking part in the killings as the default behavior and added the possibility to opt-out. Drawing on this horrific historical example of default-setting, present-day situations where defaults are used as policy-making tool to elicit desired behavior, data from a series of behavioral experiments, and theoretical considerations about leader-follower-observer relations, we (a) speculate to what extent defaults could represent a powerful leadership tool to make followers commit extreme act, and (b) alert to the potentially terribly perverse nature of defaults.