While they are unlikely to do so this offseason, the Dallas Cowboys are a franchise known for their free-agency splashes.

Since free agency became a part of the NFL, the Cowboys have become known for their ability to lure big-name players to Dallas. This talent on the part of owner Jerry Jones and others through the years has led to some of the game's best ever to land in Big D.

This list is focusing on those who made the biggest individual impact on the 'Boys during their tenure. Regardless of how good the teams they played on were, these players were key assets on their squad. They lit up the stat sheets and were always a headache for the opposing coach to game-plan for.

Let's take a look at the top free-agent signings in Cowboys history.

Leonard Davis

Leonard Davis is far from the sexiest name on this list, but he was an unexpected star in Dallas in the eyes of many during his three seasons.

Davis was awarded a huge seven-year, $49.6 million deal by the Cowboys in 2007 despite doing a whole lot of nothing in Arizona for five seasons prior. Dallas must have known that all Davis needed was a change of scenery.

The Cowboys posted their best season since 1992 in Davis' first year with the team, going 13-3 and earning a first-round bye the in playoffs.

During his three seasons with the Cowboys, Davis never failed to make the Pro Bowl and only tallied 13 penalties. The offensive line was not always the most stable during his tenure, but Davis himself was always someone Tony Romo could count on up front.

Jay Novacek

Michael Irvin, Troy Aikman and Emmitt Smith receive much of the glory for the Cowboys' success on offense in the 1990s. While their praise is well deserved, tight end Jay Novacek deserves some credit as well.

Dallas' No. 84 came over from the then-Phoenix Cardinals in 1990 and quickly became Aikman's security blanket in the passing game. None of his season numbers are astounding compared to someone like Jason Witten. Novacek did reach the Pro Bowl in five straight seasons at one point, however, and won three Super Bowl titles with Dallas.

It was Irvin and Smith's job to be the explosive weapons in Dallas' offensive attack. Novacek played his role of moving the chains with short catches and just being a consistent pass-catcher for Aikman.

Any Cowboys fan that witnessed the team's run in the '90s will attest that Novacek played an important role in that dominant offense.

Nate Newton

Just like Leonard Davis put Tony Romo's mind at ease in the pocket, Nate Newton did the same for Troy Aikman.

Newton was a member of all three Super Bowl teams for Dallas in the 1990s, joining the team in 1986 after the USFL folded. He was a six-time Pro Bowl and two-time All-Pro selection, helping anchor one of the most talented offensive lines in franchise history. In fact, Newton is one of only four Cowboys linemen to make the Pro Bowl at least six times.

While his off-the-field issues have been well noted, Newton never let those affect his play on Sundays. He was always one of the go-to options to provide holes for Emmitt Smith to run through and protected Aikman pretty darn well to boot.

Dallas fans should be forever grateful for the woes that struck the USFL. The Cowboys would have been much worse off if Newton had remained a Tampa Bay Bandit his entire football career.

Terrell Owens

People will feel how they will about Terrell Owens, but there's no question he made a (largely) positive impact on the Cowboys.

No. 81 posted at least 1,052 receiving yards in each of his three seasons in Dallas. Over that time span, Owens caught 38 touchdown passes from Tony Romo.

The Cowboys did not win a Super Bowl with Owens as their No. 1 receiver, but they did win their first playoff game since the 1990s with him. In fact, Dallas was in the playoffs in two of Owens' three seasons with the team.

While T.O. cannot be given all the credit for the team's postseason berths over that time, his stats show he was a pivotal part of the offense.

There were certainly times when it felt like Romo was forcing the ball to his top receiver over the years. There were also more than a few drops by Owens that Cowboys fans still remember to this day.

For all his faults and antics, though, Owens was a huge signing for the Cowboys back in 2006, and there's no question he helped this team win.

Deion Sanders

Playing for five teams over his NFL career, it's safe to say that Deion Sanders is probably the most successful journeyman in league history.

He's also arguably the best cornerback that has ever taken the gridiron, which makes him one of Dallas' best free-agent signings of all time.

Sanders came over from San Francisco in 1995 when he signed a seven-year, $35 million deal. He rewarded owner Jerry Jones with four Pro Bowl-worthy seasons and helped Dallas win Super Bowl XXX.

Alongside Darren Woodson and Charles Haley, Prime Time was one of the Cowboys' leaders on defense during his five seasons in Big D. When quarterbacks were bold enough to test him, Sanders recorded 14 interceptions during that time span.

Sanders was largely a hired gun at first for the Cowboys, but he stayed in Dallas for five seasons, tying his longest tenure with any team. Prime Time brought a level of intimidation to the Cowboys' secondary that wasn't as present before his arrival.