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.

Chuck Wepner

At first glance, Chuck Wepner might appear to be a strange inclusion for a list like this one. The fringe heavyweight contender from the 1970s is definitely the least famous and accomplished name on this list. 

But Wepner's 1975 Round 15 TKO loss to Muhammad Ali provided the inspiration for Sylvester Stallone's script for Rocky, the movie franchise that would go on to become nearly synonymous with the sport for many members of the general public. 

The first Rocky movie made Stallone a major Hollywood player, thus altering movie history. 

Wepner's 1976 match with professional wrestler Andre the Giant also looks quite similar to the scene starring Hulk Hogan in Rocky III, when Hogan portrayed the fictional wrestling champion Thunderlips.

I'd argue that scene was instrumental to launching the phenomena of Hulkamania. So in an indirect way, Wepner was extremely influential on the professional wrestling industry, too. 

Floyd Mayweather Jr.

Floyd Mayweather has been the most high-profile boxing star of this century. His pay-per-view weekends are considered important revenue-generating events for the entire city of Las Vegas.

For better or worse, Mayweather has been the most visible boxing star in recent years for the majority of fans in the United States. The front row sections at his fights demonstrate how much of a star Mayweather is to celebrities from the entertainment world.  

Mayweather's influence within the sport is somewhat overlooked for the present, but it will continue to become more clear as he transitions away from the sport as an active competitor in a few years.

I expect he will become heavily involved in promoting and training fighters. 

Sugar Ray Leonard

Ray Leonard emerged from the 1976 Olympic Games in Montreal as a gold medalist and a household name in the United States. From the moment he turned professional, Leonard was among the most popular and widely covered boxing stars of all time. 

Leonard was an early pioneer in boxers keeping a tight reign on their own business. Leonard worked with a number of his era's high-profile promoters, but he never gave up long-term control of his own promotional rights.

The first part of Leonard's career took place at a time when there was a large national television audience for boxing, especially an exciting hero like Leonard who had perfectly matched foes such as Roberto Duran and Thomas Hearns. Fights featuring Leonard and his biggest rivals were treated as major sports stories by the entire media.

Leonard was able to achieve a level of crossover fame that might not even be possible any longer for a contemporary star.

Mike Tyson

Mike Tyson's meteoric rise up the heavyweight ranks in the late 1980s remains among the greatest chapters in the history of boxing lore. Few fighters in history have ever generated the level of enthusiasm and excitement that Mike Tyson was able to create while still barely out of his teens.

Even today, Tyson remains the most well-known boxer to emerge in the past 30 years. His in-ring work made him a boxing icon—and his extracurricular troubles made him a TMZ-style celebrity. 

With Tyson's recent move into the promotional business, there is potential for Tyson's influence to become even more significant. Tyson's first event, at Turning Stone Casino in Verona, New York, provided ESPN2's Friday Night Fights with one of their best cards of the season. 

Sugar Ray Robinson

If you want to begin to get a good sense of the influence of the fighter born Walker Smith Jr. and known to history as Sugar Ray Robinson, simply stop to consider how widely his nickname has been copied. An impossible-to-tally number of flashy and athletic wannabes over the past 60 years have attempted to pass themselves off as Sugar Rays, or Sugar Somethings.

A very rare few have been able to pull it off. And nobody has ever supplanted the original.

Even superstars like Ray Leonard and Shane Mosley have had to accept that a certain percentage of fans will always point out that they aren't the real Sugar.

The original Sugar Ray was the best all-around boxer in the world for almost the entire 1940s and '50s. His level of dominance gave boxing writers cause to popularize the term "pound-for-pound champion."

Outside the ring, the sharp-dressed Robinson was a trendsetter. His Harlem nightclub was an important spot for jazz music and the hip post-war nightlife. 

Oscar De La Hoya

I consider Oscar De La Hoya the last of the old-school boxing phenoms.

"The Golden Boy" established himself as a household name when he won gold in the 1992 Olympics and turned professional with a great deal of media attention already focused on him. 

That used to be a common course of development for certain boxing superstars, but nobody has followed it since De La Hoya. Current super middleweight champion Andre Ward won Olympic gold in 2004, but he had to spend a half-decade establishing himself as a pro before he was anything close to a star. 

De La Hoya had the grit and talent to wage entertaining wars with the sport's biggest stars and the charisma to attract a rare female element to the sport. During the late 1990s, he became boxing's most high-profile star. 

But De La Hoya's biggest influence on the sport is ongoing. De La Hoya's Golden Boy Productions has become the most important promotional company in boxing.

Jack Dempsey

In the 1920s, following World War I, the emergence of radio and the expansion of the newspaper industry created a golden age in professional sports. And in the early part of the decade, the biggest star in sports was the heavyweight boxing champion, Jack Dempsey.

Dempsey captured the public imagination more powerfully than any champion since John L. Sullivan in the 1880s. Dempsey was the first heavyweight champion to break the $1 million and $2 million marks for gate receipts. And nobody else would come close for another generation. 

In retirement, Dempsey remained an active commentator on the sport, and his Manhattan restaurant was an institution for decades. During World War II, Dempsey helped author a hand-to-hand combat manual for the military.

John L. Sullivan

John L. Sullivan was the first America sports hero. There had been world bare-knuckle boxing champions before Sullivan, but no fighter before him had achieved such celebrity.

During his reign as the champ, the larger-than-life Sullivan was a sought-after stage performer and a guest at royal courts. His battles in the ring were covered in every detail by the emerging tabloid newspaper market, as were his carousing and exploits outside of it.

As America's first great sports star, Sullivan provided the prototype for an entire cultural category. Within boxing his most significant influence was that, after winning history's last bare-knuckle championship fight, he popularized the use of gloves. 

Muhammad Ali

The 1960s saw some of the largest social unrest in U.S. history. With the country deeply involved in the war in Vietnam, the generation coming of age stood up in large numbers to refuse participation in a military action that they felt was immoral and unjust.

When the undefeated and dominant reigning heavyweight champion, Muhammad Ali, refused induction into the army in 1967, he became a flash point for the political standoff. He was denied a license to compete and was stripped of his title. 

Ali was eventually able to return to the sport in 1970. He then became a primary player in the greatest decade in the history of the heavyweight division. His upset victory over George Foreman and his three-fight rivalry with Joe Frazier provided two of the greatest chapters in all of boxing lore. 

Over 30 years since he retired, Ali remains the biggest name associated with boxing. He is still the type of superstar who can bring out celebrities from every field, as his regular birthday celebrations routinely demonstrate.  

Joe Louis

It is hard for me to pick another boxer as more influential than Muhammad Ali, but I ultimately believe Joe Louis deserves the distinction.

When Louis faced German Max Schmeling in their 1938 rematch, it represented a seismic shift in the history of American sports and culture. With the specter of World War II hanging in the immediate future, for the first time in American history, a large percentage of white Americans rallied behind a black hero.

Louis was invited to visit the White House before the fight, where President Franklin Roosevelt told him, "We'll need muscles like yours to beat the Nazis, Joe."

For Americans to recognize a black man as one of their very best was a critical moment in the history of a multiracial nation like ours. It had influence and importance that transcended anything normally possible in sports.