An actuator arrangement comprises a rotatable shaft, a nut mounted upon the shaft and translatable along the shaft upon rotation of the shaft relative to the nut, and a lock arrangement operable to lock the shaft and nut against relative rotation, the lock arrangement comprising a lock component mounted upon one of the shaft and the nut for axial movement relative thereto but held against angular movement relative thereto, the lock component being co-operable with an abutment provided on the other of the shaft and the nut, or a component associated therewith, to lock the shaft and nut to one another against relative rotation.