Random shout out to Terry McGovern. Wins over the bantamweight, featherweight, and lightweight champions, all by knockout within the span of a few years. I think the only comparable fighter was Armstrong who is another decent idea.
I guess Lamgford's the last obvious one left. Gans, Dave Holly, Jack Blackburn, Jeanette McVea and Wills Xwhatever, Ketchel, O'Brien and Joe Walcott if you wanna be kind. A weight span of over 70 pounds