This chapter develops a robust adaptive fault-tolerant control methodology for nonlinear high-order fully actuated systems (FASs) subject to concurrent multiplicative and additive actuator faults. Unlike conventional state-space approaches, the proposed FAS approaches enables global stabilization through tailored nonlinear control laws while preserving the inherent full-actuation and decoupled characteristics of physical systems. Initiating from the tracking error dynamics in FAS framework, a tracking differentiator is engineered to computationally resolve reference signals and their temporal derivatives. The study pioneers the integration of an extended state observer within the FAS structure, significantly broadening the theoretical applicability boundaries. A Lyapunov-based fault-compensation control scheme is systematically constructed, guaranteeing uniformly ultimately bounded tracking error stability. Comprehensive benchmark simulation studies demonstrate the superior performance against existing approaches, particularly in fault accommodation scenarios.