In 2002, Houston once again became a football city as it welcomed the Texans as one of the NFL's expansion teams. Many players since have come through the team, with some making huge impacts. Several of those players have been acquired through signing them as free agents.

There's a long list of productive acquisitions that the Texans boast throughout their history, but only a few would come out as one of the best.

Here are the top-five free agent signings in Houston Texans history.

5. Gary Walker

Fun fact, Gary Walker was the only player who played for both Houston Oilers and Houston Texans.

The expansion team Texans signed defensive lineman Gary Walker in 2002. In the same year, Walker had 52 total tackles, 11 tackles for loss, and 6.5 sacks, and was selected to the Pro Bowl and an All-Pro team. In his four-year span, Williams played 46 games and totaled 84 solo tackles, three forced fumbles, and eight sacks before finishing his NFL career in 2005.

The Texans didn't have good years during Walker's stint, but he provided a defensive spark for a brand new team that needed it.

4. Antonio Smith

Needing to shore up their defense in 2009, the Houston Texas added defensive end Antonio Smith, beefing up their front line.

In 2011, Smith was named a replacement Pro-Bowler after the New England Patriots' Andre Carter was unable to play. For the season, Smith tallied 19 solo tackles and 6.5 sacks. He improved those numbers the next season with 23 solo tackles and seven sacks.

Smith played all but one game in his five-year stay with the Texans and started 78 games. Smith played in six playoff games with career playoff numbers of 12 tackles, four tackles for loss, and one sack.

3. Vonta Leach

Vonta Leach played a total of 79 games with the Houston Texans after signing him in 2006.

Throughout his four-year run as a Texan, Leach managed to grab 71 receptions with 518 yards and four touchdowns as a fullback; not only was a target on the offense, but also created rushing lanes for Houston's running game.

Leach was named to the Pro Bowl with the Texans in 2010. The fullback also was named first-team All-Pro in the same season.

2. Jonathan Joseph

After playing for the Cincinnati Bengals for five years, cornerback Jonathan Joseph signed for the Houston Texans in 2011 to the tune of five years, $48 million.

In his first season with Houston, Joseph finished with 44 combined tackles, 15 passes defended, and four interceptions and earned a Pro Bowl berth. The next season, Joseph made a leap forward by being ranked as the 73rd best player in the NFL Top 100 list, and was selected to another Pro Bowl.

In an illustrious nine-year stint with the Texans, Joseph became one of the more important defensive pieces for their team. He had totals of 421 solo tackles, five forced fumbles, and 17 interceptions and helped Houston reach the playoffs eight times.

1. Arian Foster

There's no question that the best free-agent acquisition for the Houston Texans is undrafted free agent running back Arian Foster.

From 2010-12, Foster eclipsed the 1,000 rushing-yard mark, leading the league in rushing yards, rushing yards per game, and rushing touchdowns in 2010, and being the NFL leader in rush attempts and rush TD's in 2012, and was recognized as one of the best running backs in all of football.

For his seven-year Texans career, Foster totaled 6,472 yards, 54 rushing touchdowns, to go along with 2,268 receiving yards and scoring 14 teams. Foster earned three All-Pro teams and made four Pro Bowl squads along the way, and that made him not only the best free-agent signing in Houston Texans history, but one of the best undrafted free agent signings the league has ever seen.