Andy "The Hawk" Price lost to Rudy Barro via KO2 and spent the rest of his career making a bit of sport of punishing him for it. UD10 in the rematch, and the rubber match...then a TKO6 for good measure in a 4th meeting. Done? Nope! Price vs. Barro V ended in a tenth round KO for Price. Carlos Monzón was left with his pride smarting from his early career L's to Antonio Aguilar & Alberto Massi (both in his first twenty months in the pros) - so he proceed to bash them each up thrice more over a 7-year period, thankfully getting it all out of his system before starting his MW championship reign. (as it would've been beyond the pale to pick on them in voluntary defenses once he hit his peak) Jimmy Bivins made the mistake of defeating both Archie Moore and Ezzard Charles in the nascent stages of their rivalries. Each went on to whoop him 4x (Charles outpointing him thrice and scoring a KO4, and Moore dealing him two corner retirements and one knockout on top of a majority decision victory) Jake LaMotta had the night of his life in the rematch with SRR, notching a unanimous decision. SRR beat him in their next four encounters, culminating in a vicious TKO13 beating in the "St. Valentine's Day Massacre" to relieve the Bull of his MW title. Leon Spinks was reportedly forever immortalized with his gap-toothed visage when Army boxing rival Tommy Johnson literally knocked the incisors from his mouth in the amateurs. Neon went 3-0 versus Johnson from then on. More? :think There are obvious choices like RJJ squeaking by Milkdud only to get humbled in both II & III, but let's restrict it to scenarios where it went beyond avenged twofold (reaching the point where IMO the retribution gets excessive and becomes the flogging of a dead horse)