Actuator for adjusting pitch angle of a rotor blade of a wind turbine rotatably mounted on a rotor hub, comprising a first drive element connectable with the rotor blade, a second drive element in meshing engagement with said first drive element, a lubricating device for lubricating the two drive elements and lubrication controller. A rotor with a rotor hub, on which at least one rotor blade is rotatably mounted, with actuator adjustable pitch angle. A wind turbine comprising such rotor and such actuator. Selective lubrication of zero teeth of the gear stage of the actuator considers the rotary position of the drive elements of the gear stage with respect to each other. The lubricating device includes a lubricant passage to selectively supply portion of first drive element and/or portion of second drive element meshing therewith depending on engagement position of drive elements or rotary position of rotor blade.