Butkus. Nitschke. Lambert. Singletary.
Being a middle linebacker in today's NFL isn't what it was back in the days of those Hall of Famers. Or even when Junior Seau played a decade ago.
These nasty, rugged players struck fear in their opponents, even running over their own guys to grab hold of the ball carrier and slam him to the ground.
Now there's a new breed at the position, chiseled studs combing size, speed, savvy and strength to produce similar results.
"You can't just be a big thumper," former Patriots linebacker Tedy Bruschi said. "You can't be a one-dimensional player and expect to play every down ... if anything has changed, it's just the type of athlete that has to play the position."
The man in the middle used to be the face of football, the guy in on every play who resembled a raging bull about to unload all that broad-shouldered brutality on the quivering quarterback.
That began changing once Peyton Manning, Tom Brady and Co. began warming up their arms and filling the air with passes. And with the retirements of Brian Urlacher and Ray Lewis, the end of an era has just about arrived.
Now, middle linebacker has become a situational option for many, with more and more teams running no-huddle offenses and using the entire field to set up plays. Even if the starter is good enough to stay on the field all the time, it's increasingly harder for him to have an impact on every play.
Offenses are more potent — last year marked the highest-scoring season since the 1970 AFL-NFL merger — and now defenses have to account for dual threat quarterbacks such as Robert Griffin III, Colin Kaepernick and Russell Wilson.
"Middle linebackers, first of all, they'd better be in shape and they'd better be athletic," ESPN analyst Jon Gruden said, "because these spread offenses, they can wear you out physically, running east and west, defending sideline to sideline potentially 80, 87, 92 snaps a game. And when you're a 235- or 250-pound man and you have to do that, that's very difficult."
It's not taxing just on the body, either.
"Mentally they get worn out," Gruden suggested, "because now these linebackers have to call defenses by themselves. The defensive coordinator doesn't even have time to signal a play, these offenses are up and at you so often."
Gone are the days of portly middle linebackers who looked more like the huge linemen in front of them than the defensive backs behind them.
Now, they have to be small enough to move around yet strong enough to take on fullbacks and tight ends, smart and instinctive enough to decipher offensive intentions on the fly and fast enough to cover the 53 yards between the sidelines.
"I think the day of the Levon Kirklands of the world, who was almost 300 pounds, the really large humans, is over," said John Lynch, the former hard-hitting safety now a Fox Sports commentator.
That pendulum isn't likely to swing back, either.
"You have to take into consideration that this is a passing league now," said Cris Collinsworth, the former Bengals receiver now an NBC Sports analyst. "It's going to continue to be a passing league. I think in part it's a positive thing for the league because of the concussion issue that the more you spread it out the fewer sort of head banging, short-yardage kind of fielding plays that there are.
"So I think the league will continue to open the game up more and more and provide better protection for quarterbacks, protect wide receivers, protect defenseless receivers and you'll see more of those running kind of linebackers in the game as opposed to the old Dick Butkus and the Mike Curtis that we all used to love."
Forget the 4-3 and the 3-4. The base defense in the NFL is really the 3-2 with defensive coordinators countering all the offensive innovations with three down linemen, two svelte linebackers and a bevy of DBs.
Denver defensive coordinator Jack Del Rio goes so far as to suggest the nickel cornerback should be introduced with the starters before kickoffs. After all, the middle linebacker is sometimes playing just one third of the snaps nowadays.
"If you don't have a guy who is a bona fide monster in the middle that's never going to come off the field, he can be the first guy off," said Del Rio.
On many teams, the middle linebacker is still the spine of the defense even in this age of sub packages and specialists, "and when you see the great ones, they stand out," said Lynch. Among them are Carolina's Luke Kuechly, San Francisco's Patrick Willis and Navorro Bowman, Dallas' Sean Lee and New England's Jerod Mayo.
At 6-foot, 233 pounds, Denver middle linebacker Wesley Woodyard gives up 25 pounds and four inches to Urlacher, yet he, like so many others, patterns his game after the former Bears great.
"The middle linebackers are still the dogs on the field and the guys that are still responsible for hitting and making big plays," said Woodyard. "So, you'd better have that mentality."