An active supporter is someone who takes a proactive role in supporting a cause, person, or organization. Synonyms for an active supporter include advocate, champion, enthusiast, proponent, ally, backer, fan, follower, patron, promoter, defender, sponsor, and protector. These words all convey the idea of someone who is committed and actively involved in promoting and defending the interests of another. Whether it's a political campaign, a sports team, or a charity event, an active supporter is someone who is invested in the success of the cause they support and is willing to go the extra mile to help achieve it.