Larry Holmes was pretty dirty. Scott Ledoux suffered a detached retina against Holmes, thanks to Larry's thumb. Earnie Shavers suffered a detached retina against Holmes, thanks to the thumb. Leroy Jones and Scott Frank both suffered eye injuries in their fights with Larry and blamed Holmes' thumb. Holmes actually broke his thumb hitting Bonecrusher Smith. Lots of thumbing.
How many times did Richard Steele say "no holding Ray" to Leonard without ever deducting any points in the Hagler fight?
Amnat Ruenroeng is the dirtiest fighter i've seen on coloured film by a mile, and one of the dirtiest ever ever. Astonishing filth for the modern era. His first fight with Casimero was absurd, he deployed rear-naked chokes, body-slams, knees to the balls, elbows, headlocks, just anything and everything he could think of, it was pure filth. Salido, what a boy when it comes to the blindside. Bernard Hopkins. Abner Mares. These ye olde time dirty fighters, "if that's how you boys want to play it I won't get in the way" type referees and all don't impress me. It's dirty fighting in the era of the mandatory deduction for an accidental headbutt that causes a cut. They are the true masters of the dark arts.
There was another modern guy whose name escapes me now, but I think it was Kabari Salem. His headbutts actually caused the death of an up and coming prospect at one point. Astonishingly dirty.
I believe WK broke the illegal compu-clinch record against Povetkin. He was also dirty outside the ring by tampering with the ring canvases. The mushy canvas had poor Pulev incapacitated.