Countenancer is a word that can be used to describe someone who supports or encourages a particular action or belief. However, there are a variety of synonyms that can be used in its place depending on the context. Some examples include advocate, ally, proponent, supporter, patron, defender, partner, collaborator, and champion. Each of these words carries a slightly different connotation and can be used to highlight different aspects of the support or encouragement being given. By using synonyms, writers can add nuance and depth to their writing and avoid repetition.