This chapter shifts focus to the traditional methods of modeling security threats within the context of industrial control systems (ICS). It aims to assist developers and security professionals by providing a systematic exploration of mainstream security threat models. The chapter is dedicated to understanding physical faults and information threats, categorizing them as traditional threat models. It sets the stage for Chap. 5 , which will cover cyber-physical system threat models, thus aiding in the effective identification, analysis, and mitigation of security threats throughout the security design, development, and testing phases.