29. Larry Merchant, broadcaster/journalist –Merchant is best known as the outspoken color analyst on HBO’s boxing broadcast, but he was also one of the best sports columnists of his day and wrote eloquently on boxing.
28. Bert Sugar, author/journalist/historian –Sugar has authored numerous books on boxing, was the editor of Ring Magazine and has become an in-demand historian.
27. Julio Cesar Chavez Sr., boxer – The biggest star from boxing-mad Mexico, Chavez was a mainstay on big cards in the late 1980s and throughout the 1990s. He won world titles at three weight classes and fought all the best of his era.
26. Roberto Duran, boxer – Arguably the greatest lightweight ever, Duran went on to be a dominant force as high as middleweight.
Manny Pacquiao is the biggest boxing superstar Asia ever produced
AP

25. Manny Pacquiao, boxer –One of the elite active boxers whose passionate Asian following has helped make him an international superstar and fodder for non-traditional boxing media such as CNN, Time Magazine and GQ.
24. Thomas Hearns, boxer – Hearns was one of the most exciting fighters ever and eagerly took on all comers.
23. Marvelous Marvin Hagler, boxer – Hagler was so tough, it took years for him to get a championship shot. He became one of the great middleweights of all time and was the winner in arguably the best three-round fight in boxing history, when he knocked out Thomas Hearns in 1985.
22. Cus D’Amato, trainer – D’Amato is the man who discovered Mike Tyson and built him into a fearsome title contender. He was a strategic genius and Muhammad Ali relied on his advice to defeat George Foreman in 1974. D’Amato also helped build Floyd Patterson and Jose Torres into championship fighters.
21. Jake LaMotta, boxer – LaMotta probably had the best chin in boxing. He also has a win over Sugar Ray Robinson when Robinson was in his prime, a testament to his skill. He was also the subject of the Academy Award-winning movie, “Raging Bull.”
20. Eddie Futch, trainer – Futch is arguably boxing’s greatest trainer ever and trained champions such as Joe Frazier, Larry Holmes, Alexis Arguello and Riddick Bowe. He worked into his late 80s.
19. Angelo Dundee, trainer – Dundee was the primary trainer of Ali and Leonard and was a gregarious personality who worked tirelessly to promote the fight game. He also trained George Foreman during Foreman’s comeback to boxing.
18. Mike Jacobs, promoter – Jacobs was the sport’s dominant promoter in the 1930s and 1940s and controlled the New York boxing scene. He promoted many of Louis’ fights, including Louis’ memorable match with Billy Conn.
17. Don Dunphy, broadcaster – For decades, Dunphy was the quintessential boxing play-by-play man. He called fights for years on radio before moving to television and becoming a star in that medium, as well.
16. Mike Tyson, boxer – He became the youngest heavyweight champion in history when he won the title at just 20 in 1986 and became far and away the biggest star in the sport. He still holds many of boxing’s gate and pay-per-view records.
15. Rocky Marciano, boxer – Marciano retired unbeaten as heavyweight champion. He had an exciting style and developed a passionate following.
14. Nat Fleischer, journalist – Fleischer wasn’t the best boxing writer, nor was he its finest journalist. But he founded Ring Magazine in 1922 and for the rest of his life, until his death in 1972, Ring was boxing’s foremost journalistic authority. Its influence faded somewhat in the latter part of the 20th century, but it is a big part of the sport’s history.
13. Teddy Brenner, matchmaker – Brenner became the sport’s top matchmaker, always adhering to the maxim that he wouldn’t make a match unless he’d be willing to buy a ticket to see it himself. He put together many of Ali’s bouts and is responsible for training Bruce Trampler, who himself would go on to a Hall of Fame career as a matchmaker.
12. Sugar Ray Leonard, boxer – Henry Armstrong popularized the concept of a boxer going for multiple weight division titles, but Leonard perfected it. An Olympic gold medalist with a charismatic personality, Leonard won world titles at 147, 154, 160, 168 and 175 pounds and was the biggest star in the sport after Ali retired. He later went on to become a popular television analyst and was briefly a promoter, but his influence on the game clearly came from the fans he made in his numerous big fights against the likes of Roberto Duran, Thomas Hearns and Marvelous Marvin Hagler.
11. Henry Armstrong, boxer – Considered by many to be the second-best fighter ever, Armstrong once held the featherweight, lightweight and welterweight titles simultaneously, when there were only eight weight divisions. He popularized the idea of a fighter chasing titles in multiple divisions.
10. Howard Cosell, broadcaster – Cosell was the voice of boxing for ABC and was closely tied with Ali’s career, covering not only his fights but also his battle to avoid the Vietnam War. It wasn’t long before Cosell’s presence at ringside connoted a major fight.
9. Seth Abraham, television programmer – HBO began airing boxing in 1973, five years before Abraham joined the network. But it was Abraham, whose deft touch in signing matches and his genius for putting together broadcast teams, who made HBO a major player in the sport.
8. Jack Johnson, boxer – Johnson is the boxer who opened the door in many ways for African American fighters to compete. He defeated James J. Jeffries in what was the first “Fight of the Century.” In the early part of the 20th century, he was virtually unbeatable but his career was harmed by racism and he was forced to flee to Europe.
7. Jack Dempsey, boxer – The heavyweight champion who was the first boxer to consistently attract $1 million plus gates, he became an icon in the sport whose influence lasted for decades past his retirement.
6. Sugar Ray Robinson, boxer – While many boxing fans consider Ali the greatest fighter ever, Ali always considered Robinson the best. Ali patterned his style, in and out of the ring, after Robinson. Robinson was voted the greatest boxer, the greatest welterweight and the greatest middleweight of the 20th century by The Associated Press. He was a true showman and became popular outside of just the boxing crowd.
5. Don King, promoter – King, a former numbers runner in Cleveland, is a natural showman who promoted boxing like a carnival huckster. He, along with Arum, was the dominant promoter of the second half of the 20th century and promoted 12 of the top 20 largest-grossing fights in history.
4. Bob Arum, promoter – The founder of Top Rank, Arum has been one of, if not the, top promoters in boxing for nearly 50 years. He promoted many of the sport’s superstars, including Ali, Sugar Ray Leonard, George Foreman, Marvelous Marvin Hagler, Oscar De La Hoya, Floyd Mayweather Jr. and Roberto Duran. He was the first promoter to regularly utilize boxing on cable television with his “Top Rank Boxing” series on ESPN and in his latter years, he recognized the extraordinary interest in the sport among Hispanic Americans and created a series to cater to them.
Was there ever any question who is No. 1?
AP

3. Tex Rickard, promoter – Rickard built Madison Square Garden in New York and promoted many fights at the venue which for decades would host the majority of the country’s major matches. He promoted many Jack Dempsey fights in the 1920s that had gates in excess of $1 million, figures that would be good even today.
2. Joe Louis, boxer – Louis was an American hero at a time when African Americans were decades away from achieving civil rights. The legendary sports writer, Jimmy Cannon, once wrote of Louis, “Joe Louis is a credit to race: The human race.” His 1938 victory over Max Schmeling did wonders for national morale.
1. Muhammad Ali, boxer – Ali wasn’t the greatest fighter who ever stepped into the ring. But he was among the finest and no one before or since has had the impact he’s had upon the game. His style, with his hands at his side, circling the ring and flicking out jabs, has influenced generations of fighters. His ability to promote an event and give one a reason to watch has been unmatched.

Source: Boxing’s most influential: Nos. 1-50 - Boxing - Yahoo! Sports