In recent years, there have been series that involve at least three matches. A rematch without a third fight is not a series.
Back in time, the leading series was world welterweight champion Ted ‘The Aldgate Sphinx’ Kid Lewis (189-32-14, 77 KOs) from St. George’s London, UK vs. world welterweight champion Jack ‘Boxing Marvel’ Britton (103-29-20, 30 KOs) from Clinton, New York, having fought one another twenty times.
Sam ‘The Boston Bonecrusher’ Langford (178-38-30, 126 KOs) born in Nova Scotia and fought out of Boston, Massachusetts, has been in the most series with opponents like Sam ‘The Oxnard Cyclone’ McVea (74-14-10, 60 KOs) from Oxnard, CA, fifteen times.
Harry ‘Black Panther’ Wills (70-9-3, 56 KOs) from New Orleans, LA, eighteen times. Joe Jeanette (84-9-8, 70 KOs) from Union City, NJ, fourteen times. Jeff ‘Joplin Ghost’ Clark (93-31-14, 71 KOs) from Joplin, MO, thirteen times. Jim Barry (25-26-4, 18 KOs) from Petaluma, CA, twelve times.
In more modern times there have not been series that could match those in the past especially since they fought more times in the past.
Harry ‘Pittsburgh Windmill’ Greb (108-9-3, 49 KOs) from Pittsburgh, PA, and Gene ‘The Fighting Marine’ Tunney (65-1-1, 48 KOs) from Greenwich, CT, fought one another five times. ‘Sugar’ Ray Robinson (174-19-6, 109 KOs) from Harlem, NY, fought Jake ‘Bronx Bull’ LaMotta (83-19-4, 30 KOs) from The Bronx, NY, five times.
Looking back at boxers who were in a three-fight series, we find 1960 Olympic Gold Medalist, 3-time world heavyweight champion Muhammad ‘The Greatest‘ Ali, 56-5 with 37 stoppages from Louisville, KY, who lost to WBC world heavyweight champion Ken Norton (42-7-1, 33 KOs) from San Diego, CA, and then defeated him twice. He also lost to 1964 Olympic Gold Medalist world heavyweight champion ‘Smokin’ Joe Frazier (32-4-1, 27 KOs) from Philadelphia, PA, and went on to defeat him twice.
Willie ‘The Worm’ Monroe (40-10-1, 26 KOs) from Philadelphia, PA, defeated world Middleweight champion ‘Marvelous’ Marvin Hagler (63-2, 52 KOs) from Brockton, MASS, and then lost to him twice. ‘Irish’ Micky Ward (38-13, 27 KOs) from Lowell, MASS, and Arturo ‘Thunder’ Gatti (40-9, 31 KOs) from Jersey City, NJ, fought three times. After defeating Gatti, Ward lost to him twice and retired.
Six-Division world champion Manny ‘Pac Man’ Pacquiao (62-8-2, 39 KOs) from General Santos City, PH, fought 2-division world champion Tim ‘Desert Storm’ Bradley, Jr. (33-2-1, 13 KOs) from Palm Springs, CA, three times.
He fought 4-division world champion Juan ‘Dinamita’ Manuel Marquez (56-7-1, 40 KOs) from Mexico City, MEX, three times. 1952 Olympic Gold Medalist and World heavyweight champion Floyd Patterson (55-8-1, 40 KOs) from Brooklyn, NY, fought Ingemar ‘Ingo’ Johansson (26-2, 17 KOs) from Gothenburg, SW, three times.
Canadian heavyweight champion George Chuvalo (73-18-2, 64 KOs) from Toronto, CAN, fought Willie Besmanoff (51-34-8, 19 KOs) from Munich, GER, and Milwaukee, WI, three times. He fought Canadian champion Bob Cleroux (47-6-1, 37 KOs) from Montreal, CAN, three times.