I was a rough champ..Kod in my second bout,but never again until an accident retired me after over 100 tough bouts...Who was I ?
Jackie Fields was KO'd only once and early in his career, then retired while still a top contender due to injuries sustained in a car-crash. However, he doesn't quite match your specifications.
Sandy Saddler it is! Saddler was kod in his second bout by Jock Leslie in 1944...Saddler fought 160 more times without being stopped again...An auto injury to his eye ended Saddler's career in 1956, at age 30... sidenote - about one year later I would see, Saddler ice skating on top of MSG on Sunday nights...Once shook hands with Saddler...Tough hombre to fight, as Pep would agree upon...