A compact and efficient rotary shift actuator for a shift-by-wire transmission includes a motor having a motor shaft that is rotatable about a motor axis, an output head arranged towards a second end of an output lever and adapted for connection with a shift shaft of a transmission, and a gear train for transferring torque from the motor shaft to the output head. The gear train comprises a first shaft rotatable about a first axis, a second shaft rotatable about a second axis, and the output lever pivotable about a lever axis. The gear train further includes a worm gear for transmitting torque from the first shaft to the second shaft.