Marvin Hagler

Hagler was the most relentless middleweight champion in history. He could switch between orthodox and southpaw mid-round — not as a gimmick, but as a genuine tactical weapon. When opponents adjusted to his southpaw stance, he'd switch orthodox and completely disrupt their timing. His offense was built on pressure and accumulation. He'd walk forward behind a tight guard, absorb the shots he needed to absorb, and work the body with left hooks and right hands until the opponent's output dropped. Then he'd step on the gas. Hagler's chin was granite. In 67 professional fights, he was never stopped. The left hand from southpaw was his primary weapon — a straight left or left hook that he could throw with fight-ending power from either stance. His fight with Thomas Hearns (1985) is the most violent three rounds in middleweight history: both fighters decided to brawl, and Hagler's durability won out.