This open access book details fault diagnosis, prognosis, and tolerant control for complex industrial systems. It is also dedicated to Professor Steven X. Ding for his retirement. This book proposes data-driven quality-related fault diagnosis schemes based on space projection for linear/nonlinear systems. It also introduces credible and efficient fault prognosis techniques for complex industrial systems. It combines fault detection and re-configuration toward the design of fault-tolerant control methods. It will be a useful reference for students and researchers working on fault diagnosis.