supporter, protagonist, champion, admirer, booster, friend

a person who backs a politician or a team etc.; "all their supporters came out for the game"; "they are friends of the library"

• anglophile, anglophil — an admirer of England and things English
• believer, truster — a supporter who accepts something as true
• Boswell — a devoted admirer and recorder of another's words and deeds
• Confederate — a supporter of the Confederate States of America
• convert — one who has been converted to another religious or political belief
• enthusiast, partisan, partizan — an ardent and enthusiastic supporter of some person or activity
• Francophile, Francophil — an admirer of France and everything French
• free trader — an advocate of unrestricted international trade
• functionalist — an adherent of functionalism
• Jacobite — a supporter of James II after he was overthrown or a supporter of the Stuarts
• loyalist, stalwart — a person who is loyal to their allegiance (especially in times of revolt)
• New Dealer — a supporter of the economic policies in the United States known as the New Deal
• philhellene, philhellenist, Graecophile — an admirer of Greece and everything Greek
• pillar, mainstay — a prominent supporter
• Roundhead — a supporter of Parliament and Oliver Cromwell during the English Civil War
• seconder — someone who endorses a motion or petition as a necessary preliminary to a discussion or vote
• Shavian — an admirer of G. B. Shaw or his works
• subscriber, endorser, ratifier — someone who expresses strong approval
• sympathizer, sympathiser, well-wisher — someone who shares your feelings and expresses sympathy or hopes that something will be successful
• toaster, wassailer — someone who proposes a toast; someone who drinks to the health of success of someone or some venture
• upholder, maintainer, sustainer — someone who upholds or maintains
• voucher, verifier — someone who vouches for another or for the correctness of a statement
• Whig — a supporter of the American Revolution

• advocate, advocator, proponent, exponent — a person who pleads for a cause or propounds an idea