The rapid proliferation of the Internet of Things (IoT) has revolutionized numerous industries, enabling enhanced connectivity, automation, and data exchange. However, this growing network of interconnected devices has also introduced significant security vulnerabilities, making IoT systems prime targets for cyberattacks. Threat modeling has emerged as a crucial technique for identifying and mitigating potential risks in IoT environments. This paper provides a comprehensive survey of existing threat-modeling techniques applied to IoT systems. We categorize and analyze various approaches, including asset-based, attacker-based, and software-centric models, assessing their effectiveness in addressing the unique challenges posed by IoT architectures. Additionally, we discuss the strengths and limitations of these techniques and highlight emerging trends in IoT security, offering insights into future research directions. This survey aims to equip researchers and practitioners with a deeper understanding of the evolving threat landscape in IoT and the tools available to defend against it.