There's no doubt about who the most important player on each NFL team is.
Sure, there might be a scant few exceptions, but 99 times out of 100, the quarterback is the cornerstone and person entrusted with the greatest responsibility.
But a close second is often the mike or inside linebacker...and not just because they too play in the center of the defense, just as the quarterback plays in the center of the offense.
Those "quarterbacks of the defense" call the scheme, align players and oftentimes make and shout out the adjustments.
Throughout the course of NFL history, a select few middle and inside linebackers stand head and shoulders above their peers. Here are the 10 greatest.
Teams: New Orleans Saints, Carolina Panthers
Achievements: Five-time Pro Bowler, four-time All-Pro
A decade before London Fletcher was the NFL's unappreciated, undersized, un-blockable inside linebacker, there was the late, great Sam Mills.
The leader of the famous Dome Patrol (Pat Swilling, Rickey Jackson and Vaughan Johnson) that featured an incredible group of linebackers, Mills covered the field with deceptive speed and was almost never out of place.
But as great as he was in New Orleans—where the Saints never won a playoff game and largely choked in the postseason during his tenure—Mills clinched a spot on this list for what he achieved as the wily old veteran on the Panthers expansion club of the mid-1990s.
With Mills—whose elusive pass-rushing skills continued after he left the Bayou—Carolina's defense became one of the best in the NFL in 1996, incredibly pulling within one win of earning a trip to Super Bowl XXXI.
Teams: Kansas City Chiefs
Achievements: Six-time Pro Bowler, eight-time All-Pro, one-time Super Bowl champion
The Chiefs quasi-dynasty of the late 1960s rarely receives the attention it deserves. Yes, their head coach (Hank Stram), quarterback (Len Dawson), defensive tackle (Buch Buchanan) and outside linebacker (Bobby Bell) received spots in the Hall of Fame. But, few talk about them with the same passion and praise as the Packers and Colts of the 1960s or the Dolphins, Steelers and Cowboys of the 1970s.
The same is true about their outstanding middle linebacker, Willie Lanier, who also has a spot in Canton.
Not terribly big, Lanier's strength and speed served him well in defending the run, but it was his role in creating big plays that was most beneficial to the Kansas City cause. Between interceptions and fumble recoveries, he produced 45 turnovers during his 11-year career.
Teams: Philadelphia Eagles
Achievements: Eight-time Pro Bowler, 10-time All-Pro, one-time NFL Champion
The game's last true (and one of the greatest) 60-minute man, it's quite difficult to determine which position Concrete Charlie was better at, center or middle linebacker.
While his (in)famous tackle of Frank Gifford in 1960 was his most famous moment as a middle linebacker, that was just one of hundreds. A full decade before the tackle that knocked the Hall of Famer out of football for a year, Bednarik routinely punished opposing ball-carriers and was the key to a defense that was routinely one of the best in the game.
Sure, it was a "different" game back then, and players weren't as fast or powerful nor were playbooks as intricate, but it's safe to assume that Bednarik would have dominated today, or 50 years from now.
Teams: San Diego Chargers, Miami Dolphins, New England Patriots
Achievements: 12-time Pro Bowler, 10-time All-Pro
I don't think that (especially in the modern era) Pro Bowl and All-Pro selections are always the best gauge for greatness; reputation has a way of overshadowing achievement, and too many players are named to the Pro Bowl team every year. That's why, despite his annual spot on the All-Pro and Pro Bowl teams, Seau doesn't have a higher spot on this list.
Nevertheless, he remains one of the greatest middle linebackers of all time and—during his prime—was certainly the best of his era, the 1990s.
In every facet of the game—coverage, tackling, rushing the passer and especially defending the run—Seau made opposing offenses say "ow."
Teams: New York Giants, Washington Redskins
Achievements: Five-time Pro Bowler, four-time All-Pro, one-time NFL champion
The year Huff—a guard at West Virginia—arrived in New York as a third-round pick, the Giants won the NFL championship. Two years later, they were again in the title game. In fact, during just eight seasons with the Giants, he was the centerpiece of defense that played for the championship six times.
Huff wasn't the only star on that club, but on defense, there was no more critical player.
He was every bit as tough and vicious with ball-carriers as Chuck Bednarik, every bit as complete a defender as Ray Nitschke and every bit as instinctual as Dick Butkus.
Teams: Green Bay Packers
Achievements: One-time Pro Bowler, three-time All-Pro, five-time NFL champion
It's quite an honor to be remembered as the top defender on arguably the greatest dynasty in the history of the game. And that's exactly what Nitschke was for a Packers team that won five NFL titles in the span of eight years.
Vince Lombardi's defense had great players like Willie Wood, Willie Davis and Herb Adderley, but Nitschke is the one everyone remembers. And with good reason.
He was Green Bay's answer to Chuck Bednarik, Sam Huff and Dick Butkus: an intimidating force that trounced opposing ball-carriers.
Teams: Pittsburgh Steelers
Achievements: Nine-time Pro Bowler, seven-time All-Pro, four-time Super Bowl champion
Obviously, Lambert had the benefit of playing in arguably the greatest collection of defensive talent ever assembled: Mean Joe Greene, Jack Ham, Mel Blount, L.C. Greenwood, Ernie Holmes and Donnie Shell.
But at the center of it all was Lambert, who was every bit the enforcer that Greene was and every bit the versatile run/pass defender as Ham.
Aside from being the backbone and enforcer of the defense (see: his reaction to Cliff Harris' taunting of Roy Gerela in Super Bowl X), Lambert defended the run with such aggression and reliability that any opposing running backs who managed to get by Greene up the middle often regretted it when they were met in the hole by the toothless No. 58.
But for all his intimidation and reputation as a punishing tackler, people forget just how great he was in the passing game. During one four-year period, Lambert nabbed 18 picks.
Teams: Chicago Bears
Achievements: 10-time Pro Bowler, seven-time All-Pro, one-time Super Bowl champion
To some, Singletary is the standard for middle-linebacker play.
He was a fiery leader. He covered the field with great consistency. He even rushed the passer as well as any inside linebacker in the game.
But, if there is one drawback to Singletary and one reason why he—like several of the other names on this list—can't quite lock down the top spot, it's this: Singletary benefited from playing in a team defense that is often considered the finest in NFL history.
With Richard Dent, Dan Hampton, William "The Refrigerator" Perry, Steve McMichael and Wilber Marshall playing alongside him in an extremely aggressive scheme, Singletary was almost always in a position to make plays.
And he almost always did.
Teams: Chicago Bears
Achievements: Eight-time Pro Bowler, six-time All-Pro
Unlike his Chicago successor two decades later, Dick Butkus wasn't surrounded by a wealth of talent. In fact, aside from the great Gale Sayers, there wasn't much of any talent at any position on those Bears teams.
Yet Butkus, who never appeared in a playoff game, remains one of the most iconic, most memorable, most intense names in NFL history.
The no-nonsense, angry, even violent way he played the game endeared him to many fans, including those outside of the Windy City. But his knack for creating turnovers and never being out of position endeared him to the coaching staff, and eventually, the Hall of Fame voters.
Teams: Baltimore Ravens
Achievements: 13-time Pro Bowler, 10-time All-Pro, two-time NFL Defensive Player of the Year, one-time Super Bowl champion
As great as Dick Butkus was during a relatively truncated career, Lewis is better and has been for far longer.
Consider what he was able to achieve before the arrival of truly great defenders and perennial All-Pros like Terrell Suggs, Haloti Ngata and future Hall of Famer Ed Reed. With Lewis at the helm, the Ravens put together arguably the greatest single-season defense in NFL history.
That 2000 campaign—fresh off suspicion of his involvement in a double homicide—Lewis won NFL Defensive Player of the Year and Super Bowl MVP, and it was the culmination of a five-year stint in which Lewis solidified his place as one of the game's superstars.
Now consider this: Since then, he's had nine more fantastic seasons in which the Ravens' defense was among the best in the game.
That unparalleled longevity, coupled with tremendous versatility (40.5 sacks, 31 interceptions) and the greatest sideline-to-sideline speed the game has ever seen at the inside-linebacker position, pushes him to the very top of this list.