Abstract: An actuator motor described herein has fast dynamic response capability, high torque density, high efficiency, and improved thermal and mechanical stability at high speed while minimizing weight. According to one aspect of the disclosure provided herein, an actuator motor has a rotor shaft with an array of permanent magnets attached according to a Halbach array configuration. A stator includes windings that induce a torque on the rotor shaft when rotating magnetic fields interact with the optimized magnetic flux distributions of the magnets of the Halbach array. According to various embodiments, the rotor shaft is hollow, reducing weight and rotational inertia, while improving ambient cooling characteristics of the motor.