There is a lot of them who mastered the art....Dempsey ( though I am not surew If Jack got away with it..I think it was more or less he did not care)

Hopkins,,The hip punches are his speciality...Tyson Follow with the Elbow behind the Hook...Holyfield did not really headbutt as people try and say but used to rub the top of his head against the face hard especially if a guy was swollen...

Ali...Held behind the head laid the jab out wayy too long...LaMotta you can name a dozen here...