This book compiles new developments in nonlinear dynamics, chaos theory, and complex systems analysis across physics, engineering, and applied mathematics. It provides theoretical frameworks and analytical methods for understanding, predicting, and controlling complex behaviors in natural and engineered systems. Key subspecialties include chaos control, bifurcation theory, vibro-impact oscillators, energy harvesting, fractional-order dynamics, and information-theoretic approaches. The collection bridges theory with practical applications through rigorous mathematical formulations and numerical illustrations, offering tools for researchers and practitioners in engineering, physics, biology, and data science.