No sport demands toughness more than professional football, and no sport celebrates it with as much joy, excitement, and pride. John Madden annually offers his picks of the top tough guys, and sick hits are shown repeatedly on jumbotrons nationwide and ESPN's Sportscenter. Anyone who's ever watched an NFL Films production can surely hear "the voice"—that distinctive narrator—lauding the warriors of the gridiron who lay it all out there. Imagine his voice as you say: "These tough men came to do battle today, and only the fiercest will win."

Into this atmosphere comes Neil Reynolds, public relations manager for the NFL in Europe, and his new book Pain Gang: Pro Football's Fifty Toughest Players. From early day heroes, such as Bronko Nagurski, Clark Hinkle, and Frank "Bruiser" Kinard, to Hall of Famers like Ronnie Lott, Walter Payton, and Dick Butkus, to such modern-day iron men as Emmitt Smith, Brett Favre, and Rodney Harrison, Reynolds lauds some of the toughest, meanest, most inspirational, and hardest-working men in the roughest sport. He includes interviews with teammates, coaches, opponents, and the players themselves on what it means to be tough, how they characterize toughness, and even who was the toughest of them all.

Some players fought through broken bones and tired bodies. Others laid out opponents with the hardest of hits. Still others proved themselves on the battlefields of World War II before joining this secondary field of battle. And some played hard and fast—mostly within the rules—in order to intimidate their opponents through sheer fear.

Whatever their means, these guys were tough and knew it—and they made sure everyone else did as well. Meet the Pain Gang, and you'll know it too.