First 4 that come to mind instantly. Larry Holmes George Foreman Vitali Klitschko Bernard Hopkins Duran went 18-9 after the age of 40. Robinson went 30-10 after the age of 40. Pacquiao had a good win over Thurman at age 40. Thompson beat Haye at age 40. Malinga beat Reid at age 40.
Bob Fitzsimmons wins over George Gardner and Philadelphia Jack O'Brien aged 40 were impressive. Even moreso when you consider that 40 was roughly the equivalent of 50 today for a world class athlete.
Liston would join the list if you believe that he was born earlier. Was beating Martin on points ahead of the KO and made Wepner quit.
At 54, former cruiserweight champion Firat Arslan is still active - and is so far 27-4-2 since his 40th birthday. All 4 defeats have been in world title fights!
Sonny Liston wins this hands down. He celebrated his 40th birth day avenging his defeat against Marshall by ko. For the next 9 years he was a phenom. Losing to Ali at 49 years old is not anything to be ashamed neither.
Eddie Cotton and Tiger Jack Fox fought into their 40s. In Cotton's case, he was 40 when he gave Jose Torres all he could handle in a light heavyweight title defense.
Saoul Mamby beat 37-1-1 Reyes Antonio Cruz and Glenwood Brown at 40,then beats the 17-0 Larry Barnes at 43. He also stops Gary Hinton at 42
Going off the eye test, I'd say Vitali at 40 - he was ridiculously formidable still and IMO had a few more fights left. Holmes, Foreman were great then but had faded quite a lot and I think Vitali at 40 would have edged out and old Foreman and an old Holmes.
Sugar Boy Malinga scored his 2 best wins over Nigel Benn and Reid after 40. He also won his 1st world title at 40, and second - at 42.
At this point it's not a serious competition - but He looked in his prime in his early 40s, which is impressive and very rare. He definitely beat Marco Huck first time around - and in my opinion, He beat Yoan Pablo Hernandez as well.
