This course provides a comprehensive exploration into Statistical Mechanics and Complex Systems, starting with a primer on the fundamentals of statistical mechanics and its applications in understanding complex systems. It provides an in-depth refresher on probability theory, pivotal to statistical mechanics. The course advances to a study of different types of ensembles (Microcanonical, Canonical, and Grand Canonical) and delves into the key concepts of entropy and thermodynamics. The course concludes with an analysis of the Ising model and related systems, illustrating their application and impact in the field. Throughout the course, students will be assessed in a personalized manner, considering individual learning styles, with regular feedback provided to support improvement and understanding.