As a noun motivator
is agent noun of motivate; one who motivates.
As a proper noun driver is
One who drives something, in any sense of the verb to drive .
Something that drives something, in any sense of the verb to drive .
A person who drives a motorized vehicle such as a car or a bus.
A person who drives some other vehicle.
(computing) A program that acts as an interface between an application and hardware, written specifically for the device it controls.
(golf) A golf club used to drive the ball a great distance.
(nautical) a kind of sail, smaller than a fore and aft spanker on a square-rigged ship, a driver is tied to the same spars.
* back-seat driver
* driver's license
* driver transistor
* driver tube
* driver valve
* in the driver's seat