agent, alterant, alterative, alterer, ancestor, announcer, antecedent, architect, author, avant-garde, bellwether, buccinator, bushwhacker, catalyst, catalytic agent, creator, developer, explorer, ferment, forebear, foregoer, forerunner, front runner, frontiersman, fugleman, groundbreaker, guide, harbinger, herald, innovationist, introducer, inventor, lead runner, leader, leaven, maker, messenger, modificator, modifier, original, originator, pathfinder, pioneer, point, precedent, precursor, predecessor, producer, scout, stormy petrel, trailblazer, trailbreaker, transformer, transmogrifier, vanguard, vaunt-courier, voortrekker, yeast