Game Theory is a discipline concerned with the study of interactions between two or more entities with conflicting or mixed interests. It has successfully and extensively been applied in several fields including mathematics, economics, social sciences, decision theory, and behavioural sciences. In the last few years, Game Theory has also attracted the attention of Security researchers aiming to develop quantitative analysis techniques for Network and Information Security. For them it provides a natural vehicle for a rigorous formulation of attacks, threat analysis, and reactive decision making. This presentation provides an overview of some of the proposed models in the sub-fields of Intrusion Detection, Interdependent Security, and Information Warfare.