Which "bum" has ruined most undefeated records?

[Tammy]

Bobby Crabtree gets my vote: http://boxrec.com/list_bouts.php?human_id=976&cat=boxer

With a career record Crabtree won 56 (KO 51) + lost 35 (KO 30).
Undefeated prospects he beat:

Marcellus Brown 11-0-0
King Ipitan 13-0-0
Kenny Keene 30-0-0

[SaadOffTheDeck]

Wladimir Klitschko

[Controversial]

Far from being a bum however a decent journeyman. I'm sure there are better examples however Mike 'The Bounter' Hunter springs to mind. Not all his opponents were undefeated but some big scalps for him....

Got a draw with prospect James Pritchard who was 11-0
Points win over Oliver McCall who was 11-1-0
KO win over undefeated prospect Jimmy Thunder who was 9-0
Points win over Alexander Zolkin who was 15-1-0

Others include wins over Tyrell Biggs, Ossie Ocasio, Pinklon Thomas and Dwight Muhammed Qawi however they were not undefeated at the time.

[mhagler91490]

Far from being a bum however a decent journeyman. I'm sure there are better examples however Mike 'The Bounter' Hunter springs to mind. Not all his opponents were undefeated but some big scalps for him....

Got a draw with prospect James Pritchard who was 11-0
Points win over Oliver McCall who was 11-1-0
KO win over undefeated prospect Jimmy Thunder who was 9-0
Points win over Alexander Zolkin who was 15-1-0

Others include wins over Tyrell Biggs, Ossie Ocasio, Pinklon Thomas and Dwight Muhammed Qawi however they were not undefeated at the time.

Hunter was a very good spoiler, like a HW Emmanuel Augustas, fun guy too watch as well.

[Robinson]

Good call on Crabtree.

Not so much a 'bum' but Fergusson was always a good spoiler in his time.

Buster Douglas 20-2-1 (both though were up and coming prospects)
Ray Mercer 20-1
Bobby Harris 18-0
Samson P'ohua 19-2
Obed Sullivan 29-3-1

[overhand_right]

Ferguson was a good prospect & dangerous but got derailed after the Tyson loss. From that point he became a rusty fat guy always brought in on short notice. When he was in the mood though he could beat the likes of Ray Mercer, Oliver McCall, Larry Holmes, Alex Stewart and others, despite the decisions often going the other way.

[zojo]

Isn't Zach Page the guy taking away "0s" right now?

Oh, and Willie Perryman from last decade.

[oliverfennell]

Heavyweight Willie Chapman, career record 21-29-4, beat the following undefeated guys:

0-0 Sesi Pohauhau (only a debutant, but technically undefeated)
9-0 Jason Yarosz
6-0 Grant Cudjoe
5-0 Fai Falemoe
3-0 DaVarryl Williamson
9-0 Felipe Bojorquez
9-0 TJ Wilson
8-0 Malcolm Tann
15-0-1 Preston Hartzog

Also held 7-0 Patrice L'Heureux to a draw.