I'll throw in: Ron Lyle (Foreman, Shavers, Bonavena, Ali; so many rough customers) Ali naturally. Manilla, Zaire, Norton trilogy, Shavers, Lyle, unyielding against Holmes while nearly a crippled man. Foreman. Proved that he would rather die than lose. Took insane punishment with composure in his second career. Saddler. His business was breaking bodies, and he knew a fighter has to be ready to take everything he dishes out himself. Graziano, Ketchel, LaMotta.
The epitome of it and vastly skilled chest to chest while still hammering away with an absurd workrate.