The aim of this collective volume is to study the crucial aspects related to the interconnection between the political economy of energy security and national security, which is of great importance globally, due to great volatility and complexity.Several conceptual frameworks regarding the issue of energy security are examined in order to understand the relationships between relevant parameters and then to investigate their implications for national security. Research needs to examine how energy security affects national security of nation states around the world, either as producers or consumers of energy resources.In this volume, the theory of realism is employed for the analysis of such concepts, as it emphasizes the primary importance of any given state and its national security, whereas realism is essentially a political ideology and looks to provide the proper spectrum for further analysis.The fact that the political economy of energy security and the political economy of national security are addressed as separate parts in the literature are among the main drawbacks in our effort to comprehend the issues concerned. The abovementioned results to a dichotomy that affects the ontological and epistemological essence of the two pillars of the issue in question based on our working hypothesis should be addressed in a complementary and interconnected way. Addressing both theoretical concepts and case studies to validate the argument, the authors believe that the academic level of the proposed subject is related to graduate and postgraduate studies.