ahh well bhop lost his first fight and pac was actually stopped...both are legends now... a lot more to talk about if you meant fight tho imo
Johnny Nelson lost 5 fights in the first 2 years of his career, then had another terrible 3 years where he lost 7, then he went 9 years and 21 straight victories....strange guy.
Freddie Pendleton probably takes the cake. Started his career 11-10-1, went on to win a belt and beat some damn good fighters. Of current beltholders, I'd go with Cristobal Cruz, who went from crappy Mexican journeyman to a wild volume puncher who throws so much that nobody can seem to figure him out.
when calzaghe moved up in weight he had 2 pretty bad first rds, then went on to dominate. JJM against pac also.
Also Carlos baldimir. Was nothing but a club fighter. Then ended up making a bit of money for himself