An actuator (12) includes a moving member (18) pivotally connected to a base unit (14) for rotation about an axis. The driving force for rotation of the moving member (18) relative to the base unit (14) is provided by a pair of antagonistically operating shape memory alloy (SMA) wires (48, 50) and transmitted via a torsional spring (56). An endoscope, or a snake-like robot (66), may include one or more of the actuators (12).