Holyfield taking Tyson's uppercut in round 5 and the massive overhand right in round 1 right at the start. Holyfield taking that big uppercut under the chin from Lewis Tyson taking the uppercut from Ruddock that he ducked right into in the end of round 6 of the rematch where his mouthpiece came out. Also the one where he pointed right at his chin and gave Ruddock a free swing. Ali taking shavers best overhand right, Ali taking Frazier's hook over and over and over.
Ray Mercer absorbing Tommy Morrison's left hand bang on the chin several times with barely a shrug still amazes me.
Great examples mentioned already but credit to Andy Ruiz for eating a straight right in the first AJ match that would have and should have floored anyone. Also foreman taking about 20 consecutive shots v Holyfield deserves a shout
Mayweather by Mosely. Duran hooked by Barkley. Cobb vs. Holmes and Shavers. Hagler 5 & 6 Mugabi. Pryor rd 13 Arguello Ali rd 6 Frazier Thrilla
Schmeling taking Baer's right hand in their last round. That might have been the most powerful punch landed without a kd