Luis Alberto Zarate is a current example. He's had many failed attempts at winning a light-flyweight title but did so last year, well into his 30's.
Another I can think of but many will probably disagree, is R Hatton. To me he was worn out along the way having 40 odd fights before ever having a genuine world title fight. I think he would have been better off being matched after no more than 30 odd fights. He was ready then I think, but ended up getting more wear and tear having pointless matches
I kinda agree with that myself. Hatton had had hard fights with good fighters like Eamonn Magee and Vince Phillips..... and absolutely brutalised Michael Stewart. But he had lots of filler/C level fights and blew up in weight pretty much every time. The Tszyu fight was a sensational performance, but afterwards the head movement wasn't quite there and he lunged in with his punches rather than applying pressure and mixing up between leading and drawing a lead from the opponent. The Castillo fight was a smokescreen for me, and the first five rounds against Mayweather his last good performance.
Gatti at 140? Tarver was pretty old when he won the belt but seemed at his best Moore of course Leonard beating Hagler Vitali beating Peter Tyson post prison Ali post exile