Rebel : a person who rises in opposition or armed resistance against an established government or leader.Substitute : a person or thing acting or serving in place of another.Informer : a person who informs on another person to the police or other authority.Reformer : a person who makes changes to something in order to improve it.Renegade : a person who deserts and betrays an organization, country, or set of principles.Synonym of Renegade is Rebel