1. Larry Holmes: 12.5 years, from the start of his career in 1973 until mid 1985, when he fought Michael Spinks. 2. Jack Johnson: 9.5 years, since the controversial loss against Marvin Hart until the loss against Jess Willard, in 1915. However, Johnson's opposition was pretty weak, especially during his title reign. 3. James Jeffries: 9.5 years. His whole career, although it was a short career. "The Boilermaker" didn't have so much fights, but he was unbeaten until he retired in early 1905. 4. Joe Louis: 8.5 years. Since the fight against Jack Sharkey until his first retirement. I will not count his 4 year hiatus during World War 2. 5. Rocky Marciano: 8.5 years. His whole career. Marciano fought muc more often that Jeffries, and he fought better fighters, so I think he's run is much more meaningful. 6. Wladimir Klitschko: 7.5 years. Since his fight against TOS Williamson, in October 2004, until today. If he beats Tony Thompson in his next fight, Wlad's will go 8 years unbeaten. 7. Sonny Liston: 7 years. Liston went unbeaten in 1955, after his first loss. Then, he became an active fighter again, in 1958, and went unbeaten until the first Ali loss in early 1964. 8. Muhammad Ali: 7 years. He was unbeaten in the first part of his career, from late 1960 until mid 1967. Then, in his comeback, he was unbeaten for five months before losing against Joe Frazier. 9. Joe Frazier: 7 years. He was unbeaten from late 1965 until early 1973. 10. Lennox Lewis: 6 years. Since May 1995 until April 2001. 11. Jack Dempsey: 5.5 years. Since 1918 until 1923. Then Dempsey went into semi-retirement during 3 years, and then he lost against Tunney. 12. George Foreman: 5.5 years. Since the start of his career, in 1969, until the loss against Ali in 1974.
In my opinion, the most impressive are the ones of Joe Louis, Larry Holmes and Rocky Marciano. Harry Wills also had a good one, if you don't count a DQ loss.
Great list :good How about most fights before being beaten? Depending on the opposition, that's just as impressive.
