Sergio Palma, Leo Cruz, Loris Stecca and Victor Callejas. All WBA world Super Bantamweiight champions, who had a series of fantastic fights in the 80s. (not among themselves like Chacon, Limon and Boza Edwards but Palma-Cruz 2-war of attrition, Cruz-Stecca and the two Stecca-Callejas bouts were bombs away punchatons)
There have been some amazing picks on this post! My main 3 would have been Ernesto Marcel, Eduardo Lausse and Jaime Rios but seeing as they've all been chosen I'll take the totally forgotten Panamanian Southpaw Luis Ibarra. He is a 2 time WBA Flyweight champion who lost his title in his first defence both times - he did beat 2 excellent fighters in his title winning performances though, first time around he beat Betulio Gonzalez and then he went on to beat the great Santos Laciar (in Argentina as well). Quite an up and down career at world level but an underrated fighter for sure and one that I never see mentioned.
Lew Jenkins. A hard-drinking' hell raiser and hard puncher from Texas who held the Ring lightweight title very briefly. A colorful fighter of whom, to my knowledge, no film exists.
"Cowboy" Reuben Shank, Colorado welter and middleweight who defeated Henry Armstrong and Fritzie Zivic and who was named as the fighter Rocky Graziano was asked to take a dive for. Because Rocky failed to report the 1946 bribe offer he was suspended by the New York State Athletic Commission. Shank took a terrible beating to another fighter the next year and was banned from boxing.
Flyweight champion Pone Kingpetch, the three-time world featherweight champ from Thailand, circa 1960.
i believe that Bruno Arcari reigned as WBC 140 lb champ for a while, he was on a winning streak dating back to 1966.
Lamar "Kidfire" Parks. Good middleweight who was a USA Tuesday Night Fights favorite. Lost one to Reggie Johnson, got the HIV, and his career was over.