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

agent alterant alterative alterer ancestors apprentice architect artificer artist author begetter beginner builder catalyst catalytic agent conceiver constructor craftsman creator designer deviser discoverer effector engenderer engineer executor executrix father ferment founder generator grower inaugurator industrialist initiator innovationist innovator instigator institutor inventor journeyman leaven maker manufacturer master master craftsman modificator modifier mother organizer original originator past master planner precursor prime mover producer raiser realizer shaper sire smith transformer transmogrifier wright yeast