The Collaborative International Dictionary of English v.0.48:

Inspirer \In*spir"er\, n.
   One who, or that which, inspires. "Inspirer of that holy
   flame." --Cowper.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inspirer
    n 1: a leader who stimulates and excites people to action [syn:
         galvanizer, galvaniser, inspirer]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "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