The Pittsburgh Steelers are one of two franchises in NFL history with six Super Bowls. Famously, the team won Super Bowls in the 1970s with one of the best collections of drafted players ever assembled. However, the Steelers have their fair share of impactful free agent signings.

Pittsburgh heavily favors drafting and developing its future stars. One could even argue the franchise has more mistakes in free agency than successes. However, every franchise has at least one or two noteworthy signings. This article will examine the five best free agent signings in Pittsburgh's history. Obviously, players who Pittsburgh traded for, like Jerome Bettis, won't appear.

Before starting with number five, some signings deserve honorable mentions. Kimo von Oelhoffen joined Pittsburgh before the 2000 season. The hefty interior defensive lineman spent six seasons with the franchise. He was a starter on the 2005 team that went on to win the Super Bowl. Von Oelhoffen recorded 20.5 sacks with the Steelers.

The Steelers signed cornerback Joe Haden in 2017 after the Cleveland Browns cut the former Pro Bowler. Over the past three seasons, Haden has seven interceptions and 34 passes defensed, making him the team's top coverage player during that span. Dewayne Washington, a 1998 free agent signee, also deserves recognition. After four seasons with the Minnesota Vikings, Washington spent six years with the Steelers, recording 19 interceptions.

5. Jeff Hartings C

Pittsburgh signed Hartings after the former first-round pick spent five seasons with the Detroit Lions. Hartings went on to have the best years of his career with his second team.

The Penn St. product joined Pittsburgh in 2001 and immediately took over the starting center position. He continued as the team's full-time starter there until retiring following the 2006 season.

Hartings inherited a job from three legendary Steelers. From the mid-1960s to 2000, the center spot was operated mainly by just three men: Ray Mansfield, Mike Webster, and Dermontti Dawson. All are franchise icons, and the latter two are Hall of Famers.

Hartings followed in the footsteps of his predecessors. He was a Second Team All-Pro in 2001. Years later, he made Pro Bowls in 2004 and 2005. He was also a First Team All-Pro in 2004, and Pittsburgh won their fifth Super Bowl the following season.

4. Ryan Clark FS

The LSU product entered the NFL in 2002 as an undrafted free agent. He spent two seasons with the New York Giants and two with the Washington Redskins before signing with Pittsburgh in 2006.

Clark took over the starting free safety spot alongside Troy Polamalu immediately. He remained there until 2014 when he signed a one-year deal with the Redskins to finish out his career.

A constant pro, Clark became a stalwart on Pittsburgh's most-memorable defense of the 2000s. Much like with cornerback Ike Taylor, the league and media regularly overlooked Clark when passing out awards. His 2011 Pro Bowl is the only league accolade on his resume. However, that shouldn't diminish his legacy with the team.

During his eight seasons, Clark recorded 666 combined tackles, 12 interceptions, over 40 passes defensed, three forced fumbles, and three recovered fumbles. He was on the 2008 team that won Super Bowl XLIII and the 2010 team that lost Super Bowl XLV.

3. Kevin Greene OLB

Unlike many of the other players on this list, Greene was already a monster when he joined the Steelers in 1993. Greene spent the first eight seasons of his career with the Los Angeles Rams, racking up 72.5 sacks. The 1993 team he joined already featured current and future stars like Chad Brown, Levon Kirkland, Carnell Lake, Greg Lloyd, Darren Perry, Joel Steed, and Rod Woodson.

With Greene and the Blitzburgh defense, the Steelers made a trip to Super Bowl XXX. Unfortunately, the game resulted in Pittsburgh's first Super Bowl loss in franchise history. Following the loss, Greene left for Carolina in free agency.

In his short three seasons with the Steelers, Greene bullied his way to 35.5 sacks. In 1994 he led the NFL with 14 sacks and was a First Team All-Pro. He also made Pro Bowls in 1994 and 1995.

Greene retired following the 1999 season with 160 sacks, the third-most since the stat became official in 1982.

2. James Harrison OLB

Technically, Pittsburgh signed Harrison as an undrafted free agent, which makes him eligible for this list. While he wasn't an established player and thus his signing didn't make headlines, Harrison's impact on the franchise is undeniable.

Is including Harrison on this list bending the rules? Perhaps, but he was signed and cut by the franchise multiple times. Early in his career, it looked like Harrison would not stick in the NFL. After spending 2002, his rookie year in Pittsburgh, Harrison spent 2003 with the Baltimore Ravens. He was cut again and returned to the Steelers.

He spent the 2004-2006 seasons fighting for playing time and became a full-time starter in 2007. From there, he made five straight Pro Bowls, four consecutive All-Pro teams, was the 2008 Defensive Player of the Year, and the Steelers won the Super Bowl during the 2008 season.

Harrison jumped between the Steelers and other teams during his final seasons in the NFL. In 14 seasons with the team, he recorded a franchise-record 80.5 sacks. However, since he was such a low-profile signing, Harrison yields the top spot to another linebacker from the 2000s.

1. James Farrior ILB

In 1997, the New York Jets drafted Farrior with the eighth overall pick in the first round. However, the team was quick to move on from Farrior after just five seasons. He signed with the Steelers in 2002, and so it began.

Over the next ten seasons, Farrior started 154 games for Pittsburgh. He was a mainstay on two Super Bowl-winning defenses and was also around for the Super Bowl XLV loss. Farrior racked up 1,078 combined tackles during his time with the team, the most in franchise history since the stat became official in 2001. He also put together 30 sacks, eight interceptions, nearly 50 passes defensed, 12 forced fumbles, and 10 recovered fumbles.

While Farrior wasn't as flashy as some of his more well-known teammates, he was a crucial piece of what the Steelers accomplished in the 2000s. A First Team All-Pro in 2004 and Second Team All-Pro in 2008, Farrior is one of the most underrated players in franchise history.