(n.) One who, or that which, inspirer.

abettor actuator agent animator author begetter beginner cajoler catalyst causer coax coaxer creator effector encourager energizer engenderer father firer gadfly galvanizer generator impeller inducer instigator maker mother mover moving spirit originator parent persuader pleader prime mover primum mobile producer prompter sire spark spark plug sparker stimulator tempter wheedler