This topic always makes me think of Floyd Patterson. He remained a threat and near the top of the division after he lost the title until he retired.
Holmes and Foreman Foreman's record in the second part of his career was 31-3 and it would stand that way if the fights were scored correctly by judges - Foreman was robbed against Briggs but got a gift against Shulz Holmes' record in the second part of his career was 21-3 and he beat prime Mercer, arguably deserved the nod against McCall who just stopped future ATG Lennox Lewis and was competetive against prime ATG Evander Holyfield
Fres Oquendo. He's 15 years past prime and has spent the last eight of them as a number one contender.
Frankie Duarte! Booze and drugs stalled his first run at bantamweight. Retired and then came back clean years later and reversed a KO loss to Alberto Davila (albeit controversial cut TKO) and gave Bernardo Pinango all sorts of hell in losing a close decision for the WBA Bantamweight title. Even more remarkable because he came back post prime in the same weight division he turned pro at and smaller weight fighters generally peak much earlier in their careers. Turned pro in 1973 and was kicking butt in 1987 in his title fight at 33+ years of age. Also beat 20-0 prospect and future WBA Super Bantamweight Champ Jesus Salud and lost a razor thin split decision in a non title bout to then WBA Bantamweight Champ Richie Sandoval in 1985. Remarkable comeback in many ways as all of his important fights were after 30 years of age.
Marvin "Pops" Johnson Roberto Duran is a great call. He was considered done after losing to Benitez and Laing.
Dingaan Thobela won a 168 title as a fat old guy, but was a lightweight in his prime. Corrie Sanders was also past prime when he steamrolled Wlad.
