Nagurski developed his rugged reputation as a devastating fullback for George Halas' mighty Bears outfits of the pre-World War II era, but he also was a bone-crushing linebacker. Playing in an era when pro gridders were required to perform on both offense and defense, Nagurski excelled at both. Nagurski was a part of four Bears teams that played for the NFL championship -- winning two of those games -- and was a 1963 inductee into the Pro Football Hall of Fame.

Like Nagurski, Turner was among the two-way performers in the NFL's romping-stomping leather-helmeted pre-modern era. In addition to being a superb snapper, Turner excelled at linebacker, picking off a league-high eight passes in 1942 and collecting 17 career interceptions. Turner -- who created the "Bulldog" moniker to create an aura of ferociousness of the field -- was a part of four Bears teams that won the NFL championship and was a 1966 inductee into the Pro Football Hall of Fame.

Connor played as both an offensive tackle and linebacker, but it was on defense that Connor made his most profound impact. In 1949, the defending, and eventual, NFL champion Philadelphia Eagles were steamrolling the competition behind the exceptional running back Steve Van Buren. It was an attempt to stop Van Buren that led the Bears to shift Connor to linebacker. Connor dominated as the Bears upset the champion Eagles, and the look of the NFL linebacker forever was altered. Connor was a 1975 inductee into the Pro Football Hall of Fame.

For a time, the Bears featured both Connor and George (from 1952 to 1955), and it's George who's often credited as being the first great Bears middle linebacker (a tradition carried on by Dick Butkus, Mike Singletary and Brian Urlacher). George particularly was astute at picking off opposing passers (he had 18 interceptions throughout his 15-year career -- that included one final season with the Los Angeles Rams in 1966). George was a member of two Bears teams that played for the NFL championship, including one that won the title in 1963 (the team's last title before winning Super Bowl XX). George is a 1974 inductee into the Pro Football Hall of Fame.

Butkus arguably is the standard for which any future Bears middle linebacker (or any other middle linebacker in the NFL for that matter) will be measured. Butkus was a devastating and intimidating tackler -- "violence is his lifestyle" -- but also was particularly adept at creating turnovers (he had 22 career interceptions and 25 fumble recoveries). Butkus was a 1979 inductee into the Pro Football Hall of Fame

Singletary was a cornerstone of the Bears' famous "46" defense, which the team rode to an overwhelming victory in Super Bowl XX. Following that season, Singletary was named the league's Defensive Player of the Year. He earned that honor again in 1988. While leading a reincarnation of the "Monsters of the Midway" in the 1980s, Singletary earned the nickname "Samuari Mike" for his intimidating focus with his bulging eyes putting that intensity on display for opponents at the line of scrimmage. Singletary was a 1998 inductee into the Pro Football Hall of Fame.

Urlacher could be a part of a potent linebacker duo in the Pro Football Hall of Fame class of 2018 (Ray Lewis retired following Super Bowl XLVII). Urlacher and Lewis were the standard at the middle linebacker position in the NFL for more than a decade. Urlacher opened his career winning the NFL Rookie of the Year award in 2000, and then went on to eight Pro Bowl selections and four first-team All-Pro nods. In 2005 Urlacher won the NFL Defensive Player of the Year award and a year later he helped the Bears appear in their first Super Bowl since the famous 1985 team.