Manny Pacquiao’s junior middleweight fight with Antonio Margarito is not his most significant bout in recent years, but it’s notable that the Filipino icon faces his heaviest opponent yet and will likely be the heaviest of his Hall-of-Fame career.

If Pacquiao elects to weigh-in at the contracted weight of 150, he will weigh 44 pounds more than the weight at which he turned pro as a skinny 16 year old; 38 pounds more than he weighed for his first title fight, which took place in the flyweight division.

If you think the incredible amount of weight Pacquiao has climbed in the past 10 to 15 years is unheard of, though, you’re wrong. Other fighters — many of whom are enshrined in the International Boxing Hall of Fame — have packed on as much (and even more) weight than Pacquiao has.

Len Harvey, a middleweight and light heavyweight contender during the 1930s, competed in every weight class of his day. The British hero, who began boxing professionally at the ridiculously young age of 12 and fought until he was 36, literally grew from a flyweight to a heavyweight during his career.

The hall-of-fame career of Ted “Kid” Lewis, one of the finest boxers England has ever produced, spanned 50 pounds, from 116 to 166 pounds. The two-time world welterweight champ held British and European titles at featherweight, welterweight and middleweight.

A number of former light heavyweight champs, including Bob Fitzsimmons, Georges Carpentier, Tommy Loughran and John Henry Lewis, began boxing in much lighter weight classes before they eventually grew into the 175-pound division, where they made their names.

However, these hall-of-fame-enshrined fighters fought most of their quality opposition at their heavier weights.

It’s truly rare for a fighter to climb more than 20 pounds in weight and maintain world-class level opposition as he advances to heavier divisions, as Pacquiao has accomplished. To get an idea how uncommon it is, RingTV.com has compiled a list of 10 fighters who not only climbed considerable amounts of weight during their careers but maintained very good-to-elite competition in the divisions they fought in.

The fighters have been arranged in order of those whose careers have spanned the most weight.

JAMES TONEY
Lightest weight: 157
Heaviest weight: 237
Weight span: 80
Weight classes competed in: middleweight, super middleweight, light heavyweight, cruiserweight, and heavyweight.

Best opponents at middleweight: Mike McCallum (MD 12, Draw 12), Michael Nunn (TKO 11), Reggie Johnson (SD 12), Merqui Sosa (SD 12)
Best opponents at super middleweight: Roy Jones Jr. (L 12), Iran Barkley (TKO 9), “Prince” Charles Williams (KO 12), Tim Littles (TKO 4), Tony Thornton (UD 12)
Best opponents at light heavyweight: Montell Griffin (L 12, L 12), Anthony Hembreck (TKO 7, TKO 5),
Best opponents at cruiserweight: Vassiliy Jirov (UD 12), Adolpho Washington (TKO 10), Ramon Garbey (UD 10), Jason Robinson (KO 7), Steve Little (UD 12)
Best opponents at heavyweight: Evander Holyfield (TKO 9), John Ruiz (ND 12), Hasim Rahman (Draw 12, No Contest 3), Samuel Peter (L 12, L12), Fres Oquendo (SD 12), Dominick Guinn (UD 12)

SAM LANGFORD
Lightest weight: 139
Heaviest weight: 204
Weight span: 65
Weight classes competed in: lightweight, welterweight, middleweight, light heavyweight and heavyweight.

Best opponents at lightweight: Joe Gans (UD 15), Jack Blackburn (UD 15, L 12 “newspaper decision,” D 15, D 10, D 6 “newspaper decision”)
Best opponent at welterweight: “Barbados” Joe Walcott (D 15)
Best opponents at middleweight: Stanley Ketchel (disputed 6-round “newspaper decision”), Tiger Flowers (KO 2)
Best opponent at light heavyweight: Philadelphia Jack O’Brien (TKO 5)
Best opponents at heavyweight: Jack Johnson (L 15), Harry Wills (18 bouts), Joe Jeannette (14 bouts), Sam McVey (15 bouts).

ROBERTO DURAN
Lightest weight: 119
Heaviest weight: 176
Weight span: 57
Weight classes competed in: junior lightweight, lightweight, welterweight, junior welterweight, welterweight, junior middleweight, middleweight and super middleweight.

Best opponent at junior lightweight: Ernesto Marcel (TKO 10)
Best opponents at lightweight: Ken Buchanan (TKO 13), Esteban Dejesus (L 10, KO 11, TKO 12), Yuji Suzuki “Guts” Ishimatsu (TKO 10)
Best opponents at junior welterweight: Saoul Mamby (UD 10), Edwin Viruet (UD 10), Adolfo Viruet (UD 10), Emiliano Villa (TKO 7)
Best opponents at welterweight: Sugar Ray Leonard (UD 15, TKO 8), Carlos Palomino (UD 10)
Best opponents at junior middleweight: Thomas Hearns (TKO by 2), Wilfredo Benitez (L 15), Pipino Cuevas (TKO 4), Davey Moore (TKO 8)
Best opponents at middleweight: Marvelous Marvin Hagler (L 15), Iran Barkley (SD 12), Leonard (UD 12), Hector Camacho (UD 12), William Joppy (TKO by 3)
Best opponents at super middleweight: Vinny Pazienza (L 12, L 12), Jorge Castro (L 10, UD 10)

THOMAS HEARNS
Lightest weight: 144
Heaviest weight: 191
Weight span: 47
Weight classes competed in: welterweight, junior middleweight, middleweight, super middleweight, light heavyweight and cruiserweight.

Best opponents at welterweight: Ray Leonard (TKO by 14), Pipino Cuevas (KO 2), Randy Shields (TKO 13), Bruce Curry (KO 3), Saensak Muangsurin (TKO 3), Angel Espada (TKO 4), Harold Weston (RTD 6)
Best opponents at junior middleweight: Wilfred Benitez (MD 15), Roberto Duran (TKO 2),
Best opponents at middleweight: Marvin Hagler (TKO 3), Iran Barkley (TKO by 3), Juan Roldan (KO 4), Doug DeWitt (UD 10), James Shuler (KO 1), Murray Sutherland (UD 10)
Best opponents at super middleweight: Leonard (D 12), Michael Olajide (UD 12), James Kinchen (MD 12)
Best opponents at light heavyweight: Virgil Hill (UD 12), Dennis Andries (TKO 10), Barkley (L 12)
Best fought at cruiserweight: Nate Miller (UD 12), Uriah Grant (TKO by 2), Andrew Maynard (KO 1)

ROY JONES JR.
Lightest weight: 153
Heaviest weight: 193
Weight span: 40
Weight classes competed in: middleweight, super middleweight, light heavyweight, cruiserweight, and heavyweight.

Best opponents at middleweight: Bernard Hopkins (UD 12), Thomas Tate (TKO 2), Jorge Castro (UD 10), Jorge Vaca (KO 1)
Best opponents at super middleweight: James Toney (UD 12), Thulani “Sugar Boy” Malinga (KO 6), Eric Lucas (TKO 11), Vinny Pazienza (TKO 6), Antoine Byrd (TKO 1), Tony Thornton (TKO 3), Glenn Thomas (TKO 8), Percy Harris (TKO 4), Bryant Brannon (TKO 2)
Best opponents at light heavyweight: Mike McCallum (UD 12), Antonio Tarver (MD 12, TKO 2, L 12), Hopkins (L 12), Glen Johnson (KO’d 9), Joe Calzaghe (L 12), Virgil Hill (KO 4), Montell Griffin (KO 1, DQ 9), Felix Trinidad (UD 12), Reggie Johnson (UD 12), Julio Gonzalez (UD 12), Clinton Woods (UD 12), Lou Del Valle (UD 12), Jeff Lacy (TKO 10), David Telesco (UD 12), Eric Harding (TKO 10), Otis Grant (TKO 10), Merqui Sosa (TKO 2), Omar Sheika (TKO 5), Anthony Hanshaw (UD 12)
Best opponents at cruiserweight: Danny Green (TKO’d 1)
Best opponents at heavyweight: John Ruiz (UD 12)

MANNY PACQUIAO
Lightest weight: 106
Heaviest weight: 145
Weight span: 39
Weight classes competed in: flyweight, junior featherweight, featherweight, junior lightweight, lightweight, junior welterweight and welterweight.

Best opponents at flyweight: Chatchai Saskul (KO 8), Chokchai Chockvivat (KO 5)
Best opponents at junior featherweight: Lehlohonolo Ledwaba (TKO 6), Agapito Sanchez (Tech. Draw 6), Jorge Eliecer Julio (TKO 2), Wethya Sakmuangklang (TKO 6), Fahprakorb Rakkiatgym (KO 1)
Best opponents at featherweight: Marco Antonio Barrera (TKO 11), Juan Manuel Marquez (Draw 12)
Best opponents at junior lightweight: Erik Morales (L 12, TKO 10, TKO 3), Marquez (SD 12), Barrera (UD 12), Oscar Larios (UD 12), Jorge Solis (KO 8)
Best opponent at lightweight: David Diaz (TKO 9)
Best opponent at junior welterweight: Ricky Hatton (KO 2)
Best opponents at welterweight: Oscar De La Hoya (TKO 8), Miguel Cotto (TKO 12), Joshua Clottey (UD 12)

MICKEY WALKER
Lightest weight: 139
Heaviest weight: 174
Weight span: 35
Weight classes competed in: welterweight, middleweight, light heavyweight and heavyweight

Best opponents at welterweight: Jack Britton (UD 15, L 12 “newspaper decision”), Lew Tendler (UD 10)
Best opponents at middleweight: Harry Greb (L 15), Tiger Flowers (UD 10), Young Corbett III (L 10), Mike McTigue (UD 12 “newspaper decision”), Ace Hudkins (SD 10, UD 10)
Best opponents at light heavyweight: Tommy Loughran (L 10), Maxie Rosenbloom (L 15, UD 10), Paul Berlenbach (UD 10), McTigue (TKO 1)
Best opponents at heavyweight: Jack Sharkey (D 15), Max Schmeling (KO by 8), Paolino Uzcudun (UD 10), and King Levinsky (UD 10).

JIMMY MCLARNIN
Lightest weight: 112
Heaviest weight: 147
Weight span: 35
Weight classes competed in: flyweight, featherweight, lightweight, junior welterweight, welterweight

Best opponent at flyweight: Fidel Labara (UD 10, UD 4, D 4)
Best opponent at featherweight: Pancho Villa (W 10)
Best opponents at lightweight: Sammy Mandell (L 15), Sid Terris (KO 1), Al Singer (KO 3), Luis Kaplan (KO 8)
Best opponent at junior welterweight: Al Singer (KO 3)
Best opponents at welterweight: Barney Ross (SD 15, L 15, L15), Tony Canzoneri (UD 10, L 10), Benny Leonard (TKO 6), Lou Ambers (UD 10), Young Corbett III (TKO 1), Mandell (UD 10, UD 10), Lou Brouillard (L 10), Billy Petrolle (UD 10, UD 10, L 10), Ruby Goldstein (KO 2)

OSCAR DE LA HOYA
Lightest weight: 128
Heaviest weight: 160
Weight span: 32
Weight classes competed in: junior lightweight, lightweight, junior welterweight, welterweight, junior middleweight, and middleweight.

Best opponents at junior lightweight: Jimmi Bredahl (TKO 10), Giorgio Campanella (TKO 3)
Best opponents at lightweight: Genaro Hernandez (TKO 6), Rafael Ruelas (TKO 2), James Leija (TKO 2), Juan “John John” Molina (UD 12), Jorge Paez (TKO 2), Troy Dorsey (TKO 1)
Best opponents at junior welterweight: Julio Cesar Chavez (TKO 4), Miguel Angel Gonzalez (UD 12)
Best fought at welterweight: Pernell Whitaker (UD 12), Manny Pacquiao (TKO by 8), Felix Trinidad (L 12), Shane Mosley (L 12), Ike Quartey (SD 12), Chavez (TKO 8), Hector Camacho (UD 12), Oba Carr (TKO 11), Wilfredo Rivera (TKO 8), Arturo Gatti (TKO 5)
Best opponents at junior middleweight: Floyd Mayweather Jr. (L 12), Fernando Vargas (TKO 11), Mosley (L 12), Ricardo Mayorga (TKO 6), Javier Castillo (UD 12), Yory Boy Campas (TKO 7)
Best opponents at middleweight: Bernard Hopkins (TKO by 9), Felix Sturm (UD 12)

MIKE MCCALLUM
Lightest weight: 150
Heaviest weight: 182
Weight span: 32
Weight classes competed in: junior middleweight, middleweight, light heavyweight, and cruiserweight.

Best opponents at junior middleweight: Donald Curry (KO 5), Julian Jackson (TKO 2), Milton McCrory (TKO 10), Ayub Kalule (TKO 7), Sean Mannion (UD 15), Luigi Minchillo (TKO 13)
Best opponents at middleweight: James Toney (Draw 12, L 12), Sumbu Kalambay (L 12, SD 12), Steve Collins (UD 12), Michal Watson (KO 11), Herol Graham (SD 12)
Best opponents at light heavyweight: Roy Jones Jr. (L 12), Jeff Harding (L 12), Fabrice Tiozzo (L 12)
Best opponents at cruiserweight: Toney (L 12)

HONORABLE MENTION:

Henry Armstrong — the all-time great three-division champ fought from 120-148 pounds (a 28-pound span), taking on Petey Sarron (KO 6), Baby Arizmendi (L 10, L 12), Midget Wolgast (UD 10), and Rodolfo “Baby” Casanova (KO 3, LF 4) at featherweight; Lou Ambers (SD 15, L 15), Beau Jack (L 10), Albert “Chalky” Wright (TKO 3), Mike Belloise (KO 4, UD 10), Pete DeGrasse (KO 10), and Tony Chavez (TKO 1, KO 10) at lightweight; Sugar Ray Robinson (L 10), Barney Ross (UD 15), Fritzie Zivic (L 15, TKO’d 12), Sammy Angott (UD 10), Lew Jenkins (TKO 6, TKO 8), and Juan Zurita (KO 2) at welterweight; and Ceferino Garcia (Draw 10) at middleweight.

Tony Canzoneri — the all-time great three-division champ fought from 117-143 pounds (a 26-pound span), taking on Bud Taylor (Draw 10, L 10) at bantamweight; Johnny Dundee (UD 15) and Benny Bass (SD 15) at featherweight; Lou Ambers (UD 15, L 15, L 15), Jackie “Kid” Berg (KO 3, UD 15, L 10), Kid Chocolate (KO 2, SD 15), Baby Arizmendi (UD 10), Sammy Mandell (L 10), Al Singer (KO 1, D 10), Billy Petrolle (UD 15, L 10) and Frankie Klick (TKO 9 UD 10) at lightweight; Barney Ross (L 15, L 10), and Johnny Jadick (UD 10, L 10) at junior welterweight; and Jimmy McLarnin (UD 10, L 10) at welterweight.

Sugar Ray Leonard — The five-division titleholder and hall of famer fought from 141-165 pounds (a 24-pound span), taking on Roberto Duran (L15, TKO 8), Thomas Hearns (TKO 14), Wilfredo Benitez (TKO 15), Randy Shields (UD 10), Andy Price (KO 1), Armando Muniz (TKO 6) and Pete Ran zany (TKO 4) at welterweight; Terry Norris (L 12), and Ayub Kalule (TKO 9) at junior middleweight; Marvelous Marvin Hagler (SD 12), Duran (UD 12), and Hector Camacho (TKO by 5); and Hearns (Draw 12) and Donny Lalonde (TKO 9) at super middleweight.

Pernell Whitaker — The four-division titleholder and hall-of-famer fought from 134-155 pounds (21-pound span), taking on Azumah Nelson (UD 12), Jose Luis Ramirez (UD 12, L 12), Roger Mayweather (UD 12), Greg Haugen (UD 12), Freddie Pendleton (UD 12), and Jorge Paez (UD 12) at lightweight; Rafael Pineda (UD 12) and Harold Brazier (UD 12) at junior welterweight; Julio Cesar Chavez (Draw 12), Felix Trinidad (L 12), Oscar De La Hoya (L 12), and Buddy McGirt (UD 12, UD 12) at welterweight, and Julio Cesar Vazquez (UD 12) at junior middleweight.

Floyd Mayweather Jr. — The five-division titleholder has fought from 129-150 pounds (21-pound span), and taken on Genaro Hernandez (TKO 8), Diego Corrales (TKO 10), Jesus Chavez (TKO 9), Carlos Hernandez (UD 12), Gregorio “Goyo” Vargas (UD 12), and Angel Manfredy (TKO 2) at junior lightweight; Jose Luis Castillo (UD 12, UD 12), Victoriano Sosa (UD 12), and Philip Ndou (TKO 7) at lightweight; Arturo Gatti (TKO 6) and DeMarcus “Chop Chop” Corley (UD 12) at junior welterweight; Shane Mosley (UD 12), Zab Judah (UD 12), Ricky Hatton (TKO 10), Carlos Baldomir (UD 12), and Sharmba Mitchell (TKO 6) at welterweight; and Oscar De La Hoya (SD 12) at junior middleweight.