In composing this list I have tried to give some weight to both influence within the sport and influence beyond the ring, in the greater society and culture. So fighters from earlier eras, when the sport enjoyed greater prestige, have a certain advantage here.
I have tried to consider how strongly a fighter has been associated with boxing in the public consciousness, along with the degree to which a fighter has made the public more aware of boxing itself. But I have weighed heavily towards fighters who ended up influencing society in ways that transcend sports.
This is also a list with a U.S. bias. "Most influential" is mainly defined here as most influential within the United States.