Despite the brutal results of power conflicts, nations still constantly engage themselves in it. Important leaders throughout the world, particularly from the twentieth century who exercised coercive powers to bring change in the society, are studied in this chapter. An effort is made to study not only the impact of their policies and how far they were successful in achieving them but also the psychology behind the choice of their actions. The leaders studied here are Adolf Hitler, Vladimir Lenin, Mao Tse Tung, Fidel Castro and Ernesto Guevara.