A variable pliability actuator is provided to move a movable component including two electric rotary motors, at least one output shaft connected to be set in rotation by the motors around a rotation axis, an elastic transmission system to enable motion transfer from the motors to the output shaft and to vary the pliability the output shaft, a control unit to adjust at least the pliability of the output shaft through the elastic transmission system, and a holding structure to hold at least the motors, the elastic transmission system, the output shaft and the control unit. The holding structure has a driving output placed at the outer surface controlled by the output shaft and connected to set the movable component in rotation about the rotation axis, at least one stiff coupling element to enable a stiff connection of the holding structure, and a support output opposite the driving output, substantially coaxial with the rotation axis and partly housing and stabilizing the rotation of the movable component.