A high density actuator, comprising a housing assembly composed of a first housing element containing a motor stator and a second housing element containing a gear reduction mechanism, a rotational core positioned at the center of the housing assembly, the rotational core being composed of a motor rotor and a transmission input operatively connected to the motor rotor, a transmission output positioned between the transmission input and the housing assembly, the transmission output forming an actuator output, a torque transfer output operatively connected to the actuator output and a center shaft connected to the torque transfer output in its center and in rotational contact with the first housing element, the center shaft passing through the transmission output, rotational core and second housing element to ensure proper radial and axial alignment.