Emile Griffith
Emile Griffith was a world champion at welterweight and middleweight multiple times. Some even consider him a three-division champion, though a junior middleweight title was not yet recognized.
Griffith is best known for his three-fight series with welterweight champion Benny Paret in which Griffith won two of the three. Their third fight was highly controversial, as Paret died due to injuries sustained in the bout.
Griffith also had notable trilogies with Luis Rodriguez and Nino Benvenuti. He also prominently fought, but lost to, Carlos Monzon and Jose Napoles, both fighters on this list.