A bruising running back who obliterated tacklers, Nagurski helped lead the Bears to NFL championships in 1932, 1933 and 1943. At 6-2 and 235 pounds, Nagurski would be a big running back in today's NFL; when he played he was larger than most linemen.

Feared by both opponents and teammates alike, Kreutz was an intimidating force who anchored the Bears offensive line for more than a decade. During a brawl with the Vikings, he approached Minnesota's sideline and did the "Crane Stance" from the "The Karate Kid." 

The Hall of Famer flattened would-be tacklers as a Bears tight end and brought that same tenacity and attitude to his job as the team's head coach. Ditka won NFL championships in both roles, leaving bruised and battered opponents in his wake.

Nicknamed "Danimal" because he was part-man and part-animal, the Hall of Fame defensive lineman leveled opposing quarterbacks and ballcarriers from both the tackle and end positions with the force of a runaway freight train.

The giant 6-8, 257-pound Hall of Famer revolutionized the defensive end position as a take-no-prisoners pass rusher. One opponent once advised a teammate, "Don't cut him, and if he falls down, help him up and say, 'Nice play, Mr. Atkins.'"

Mike Ditka once called "Mongo" the toughest player he ever coached. McMichael sharpened hunting knives in the locker room to scare away reporters. Asked to support a political candidate after a game, he stuck a campaign pin in his bare chest.

Dubbed "the meanest man in football" by Collier's Weekly magazine in 1950, Ed Sprinkle terrorized opponents with the Bears from 1944-55. He stopped ballcarriers in their tracks with a powerful forearm shiver, which earned him the nickname "The Claw."

The hard-hitting safety played with such a reckless abandon—sacrificing his body to blow up receivers—that today he'd earn so many fines he'd have to take out a loan. Opponents would rather see "Psycho" in an abandoned hotel than Plank over the middle.

After breaking 16 helmets with crushing hits at Baylor, "Samurai Mike" played with relentless aggression and violence with the Bears that was reflected in his wild, darting eyes that appeared to be bugging out of his head.

Still considered by many to be the most ferocious player in NFL history, the Chicago native was a fierce and intimidating middle linebacker. Said one opponent: "Every time he hit you, he tried to put you in the cemetery, not the hospital."