Well, name them. I'll start with the obvious one: Oleksandr Usyk. His 1st pro fight occured when he was almost 27
Don't remember exact numbers Norton was early 20's I believe and Ron Lyle was 29 or 30! Can't get over Lyles age.
Qawi indeed had his 1st pro fight after he turned 25. Considering the facts that he started late and was very short even for LHW (just 5'6''), he must have been enormously gifted in other areas to become a great fighter.