paladin

a person who actively supports or favors a cause an idealistic paladin seeking better treatment for the homeless Synonyms advocate, advocator, apostle, backer, booster, champion, expounder, espouser, friend, gospeler (or gospeller), herald, hierophant, high priest, exponent, promoter, proponent, protagonist, supporter, true believer, tub-thumper, white knightRelated Words loyalist, partisan (also partizan), stalwart; adherent, cohort, disciple, follower; interpreter; applauder, cheerleader, encourager, fellow travelerNear Antonyms enemy, foe, rival; belittler, critic, faultfinderAntonyms adversary, antagonist, opponent