I hesitate to say of all time because it hasn't run out yet but some examples please Gents. Lets start near the beginning with English welterweight "Legend" and I use that word advisedly TED "Kid" Lewis

Here he is at 146lb against 200 lb Heavyweight Tom Gummer

and again against the much better known French Heavy Georges Carpentier a fight which despite being at a distinct weight disadvantage Ted could well have won were it not for George's Mayweatheresque*sucker punch whilst the ref tries to stop George holding




* Floyd of course did not need a suckerpunch to prove his dominance of Ortiz and technically it could be seen as a perfectly legitimate consequence of Victor acting like a douche but that's the job of another thread to discuss