Which fighters throughout history have a fantastic resume despite have had not all that many fights, say under 40.
Joe Frazier: Bonave (twice), Machen, Jones, Chuvalo, Mathis, Ramos, Quarry (twice), Ellis (twice), Foster, Ali, and Bugner
Michael Spinks: Murray Sutherland (twice), Yaqui Lopez, Marvin Johnson, Eddie Mustafa Muhammad, Dwight Muhammad Qawi, Larry Holmes (twice), and Gerry Cooney
I don't think Frazier and Spinks have the most impressive resumes for guys with records under 40, but theirs are pretty good.
Palomino, Fenech and Andre Ward all amassed pretty impressive records in under 40 fights. Froch too, come to think of it.
Jose Torres (the light heavyweight) had a little over 40 bouts, and he beat lots of top middlweights and light heavyweights, and even a couple decent heavies
Good ones mentioned. Of non active fighters, Kostya Tszyu did a whole lot in not a lot of fights. 34 fights total. He was probably good enough to win his title in his 1st fight let alone his 14th. Masao Oba is another who crammed a lot into under 40 fights.
James Jeffries is probably the great with the fewest fights. Something like 24. Fenech is probably next with 32. Lomachenko will obviously make the list but he’s still active.
Lomachenko is an obvious answer even though he's still active. I don't think he'll reach 40 fights by the time he retires. I guess you can add Naseem Hamed to the list too.