Middleweight Harry Greb, Welterweight Mickey Walker, Featherweight Henry Armstrong fighting and winning impressively beyond their original weight classes up to the Middleweights and the Heavyweights.
In more recent times:
Dwight Muhammad Qawi vs. Matthew Saad Muhammad 1 & 2
Dwight Muhammad Qawi vs. Piet Crous
Dwight Muhammad Qawi vs. the Davis Brothers
Dwight Muhammad Qawi vs. Leon Spinks
Roberto Duran vs. Iran Barkley
Manny Pacquiao vs. Joshua Clottey and Tony Margarito
Floyd Mayweather vs. Carlos Baldomir and Oscar de la Hoya
Shane Mosley vs. ODLH and Fernando Vargas
James Toney vs. Vasili Jirov and Hashim Rahman and Evander Holyfield
David Tua vs. everyone
Mike Tyson vs. everyone above 6 feet and 230 lbs.
Evander Holyfield vs. Nicolae Valuev
Roy Jones vs. John Ruiz and Antonio Tarver 1
Floyd Mayweather vs Jose Luis Castillo
I will answer this a little more thoroughly later but there are several old time fighters that come to mind as far as beating bigger fighters. One was Harry Greb and the other Mickey Walker. Greb spent his entire career at a fighting weight of between 158-168 lbs and fought men in the top 3 weight classes middle, light heavy and heavyweight divisions. He was constantly figting and training so his weight didn't fluctuate compared to fighters toeday who don't fight as frequenstly and he had the ability to easily make the weights. Greb had the ability to fight and beat heayweights despite weighing 160 lbs and would fight men who sometimes outweighed him by over 30 lbs or more. He also would fight light heavys who would usually outweigh him by 10-15 lbs. He simply defeawted all comers regardless of size which is one of the incredible accomplishments in fistic history because of his natural speed, great conditioning and one of the greatest chins of all tme too and wanted to even take on Heavyweight Champion Dempsey who simply refused to face him in the ring though they did have some all out sparring sessions that Greb got the better of. Here is a list of some of the bigger men Greb faced and defeated:
Greb defeated
Gene Tunney
Tommy Gibbons
Ed "Gunboat" Smith
Willie Meehan
Billy Miske
Bill Brennan
Kid Norfolk
Jack Dillon
Battling Levinsky
Tommy Loughran
Maxie Rosenbloom
Captain Bob Roper
James Slattery
Mike McTigue
Chuck Wiggins
Batley Madden
Jack Renault
All these men were either heavys or light heavys and some were Hall of famers and future Champs.
Also Mickey Walker who took on Harry Greb in their famous battle often took on bigger men all the way up to heavyweight though not with the success of Greb. He did defeat Bearcat Wright who outweighed him by over 100 lbs and held Jack Sharkey to a draw and fought a brave fight vs Max Schmeling.
Other fighters such as Jack Dempsey who of course is well known for beating the much larger Luis Firpo and Jess Willard deserve mention along with Rocky Marciano, Henry Armstrong, Stanley Ketchel and Sam Lanford.
Among modern fighters Manny Pacquiao has defeated bigger fighters too along with Evander Holyfied in their remarkable careers.
Nearly every fight of tyson.. Hagler,leonard vs hearns, dempsey has a few, can't think of top of me head
What were some good boxing matches between a big boxer vs a small boxer and the smaller boxer won the fight?
