What might have been? This is the question we are often left with when star athletes leave the sport early – especially in professional football. Any fan of the NFL knows that injuries are part of the game, and many of the biggest names in football have managed to come back from some pretty debilitating injuries. However, some of football’s brightest stars have seen their careers completely derailed by some truly horrific injuries. It leaves fans wondering what might have been accomplished had those injuries not occurred. What great heights might have been reached if these player had never gotten hurt? Here we look at 10 great NFL players whose careers were cut tragically short by injuries, regardless of age.

10. Joe Theismann, Age 36

Joe Theismann is certainly not the youngest player on this list, but he was enjoying a late resurgence when a truly gruesome injury cut his career instantly short and forced him into retirement. Under Redskins head coach Joe Gibbs, Theismann experienced a career renaissance, being named to the Pro Bowl in 1982 and 1983, and guiding the Redskins to three straight playoff appearances from 1982 through 1984, including two Super Bowl appearances. Theismann was finally getting the recognition he deserved as a top QB, but it all came crashing down during a game against the New York Giants in 1985. Linebacker Lawrence Taylor sacked Joe Theismann, and in the process snapped Theismann’s tibia and fibula, breaking the quarterback’s leg like a twig. The injury was so bad that Taylor began to scream for medical personnel to help Theismann and even shed tears. The compound fracture toTheismann’s leg forced him immediately into retirement. He never took another snap.

(AP Photo/P.Binks, FILE)

9. Michael Irvin, Age 32

Michael Irvin was arguably the best wide receiver in the NFL in the early and mid-1990s. A member of the Super Bowl winning Dallas Cowboys, Irvin was NFL royalty when his career was cut short at age 32 due to injury. Irvin was still a productive player into the late 1990s when he got hurt. In 1997 and 1998, Michael Irvin still had at least 74 receptions and over 1,000 yards receiving. But in the fourth game of the 1999 season, against the Philadelphia Eagles, Irvin was tackled from behind and violently thrown to the ground head first. The Philly fans solidified their reputation for cruelty as they cheered while Irvin was carried off the field on a stretcher, wearing a neck brace. Irvin sustained a spinal cord injury that was bad enough it forced him into instant and early retirement. He never put a football uniform on again.

(AP Photo/Eric Gay)

8. Priest Holmes, Age 29

Remember Priest Holmes? You could be forgiven if you forgot about this dynamic player who lit up the NFL in the early 2000s as one of the game’s top running backs. In 2001, coming off two mediocre seasons with the Baltimore Ravens, Holmes signed a modest free agent contract with the Kansas City Chiefs. The Chiefs helped turn Holmes’ career around and got a great return on their investment in the process. Beginning with the 2001 season, Holmes ran for over 1,400 yards in three consecutive NFL campaigns. He had 21 rushing touchdowns in 2002 alone, and set the NFL record for rushing touchdowns in a single season with 27 in 2003. Holmes was actually on pace to break that record again in 2004, running for 14 touchdowns in only eight games, when he suffered a season-ending injury that would prove to be fatal to his career. In 2005, Holmes missed nine games after suffering an injury to his spinal column. He then missed all of the 2006 season trying to recover, and managed to play in only a couple of games in 2007 before announcing his retirement at age 29. Holmes retired as the Chiefs’ all-time leader for career rushing touchdowns (76), total touchdowns (83), and career rushing yards (6,070).

(AP Photo/Charlie Riedel)

7. Steve Young, Age 37

San Francisco 49ers quarterback Steve Young is the oldest player on this list. He called it quits at age 37 due to injury. You may think that retiring at 37 is hardly leaving the game early, but Young was still one of the game’s elite quarterbacks and seemed to be in his prime when injury sidelined him for good. Young made it to the Pro Bowl every season between 1992 and 1998 and won the Super Bowl in 1994. The 1998 campaign was arguably the best season of his career – throwing for career highs in passing yards (4,170) and passing touchdowns (36). That season, Young led the 49ers to an NFC Divisional Playoff appearance, where his 49ers defeated Brett Favre and the Green Bay Packers. But early in the 1999 season, Young was knocked out of the game after being hit by Arizona Cardinals defensive back Aeneas Williams. He suffered a major concussion – his second concussion of the still early season — and at least the fifth of his career. Doctors felt that the repercussions of Young continuing to play football after such a devastating injury were just too dangerous. The 49ers brass threatened to release Young if he attempted to get back on the football field, so he promptly retired and left the game he loved.

(AP Photo/Lenny Ignelzi, File)

6. Sterling Sharpe, Age 28

Sterling Sharpe is another great football player who has been forgotten a bit in the fog of time. In 1994, the Green Bay Packers wide receiver was named to his third straight Pro Bowl after catching a league-leading 18 touchdown passes, along with 90 receptions for 1,119 receiving yards. But sadly, in Week 15 of that season – playing against the Atlanta Falcons — Sterling Sharpe’s head was jarred back on a block, and the injury only worsened the following week during Green Bay’s regular season finale. The Packers team doctors discovered what they called “an abnormal loosening of the first and second cervical vertebrae,” in Sharpe’s spine, and medical personnel advised that he end his football career right away. Sharpe was only 28-years-old at the time, and in the prime of his career. He missed an eventual Super Bowl victory by the Packers just two seasons later. If not for that injury, Sharpe could have gone down as one of the all-time greats in Packers lore.

5. Terrell Davis, Age 29

Probably as much as any player in NFL history, running back Terrell Davis’ career can be characterized as a meteoric rise followed by a sudden crash. After being picked in the sixth round of the 1995 NFL Draft by the Denver Broncos, Davis shot up the team’s depth chart during his first season in the NFL – eventually winning the starting job. Davis rushed for 1,117 yards and seven touchdowns in his rookie season. Over the following three seasons, Davis rushed for more than 1,500 yards and 15 touchdowns in each campaign. His 1,750 yards rushing and 15 touchdowns in 1997, and 2,008 yards and 21 touchdowns in 1998, helped propel the Denver Broncos to two Super Bowl victories (plus some guy name John Elway). Davis was named MVP of Super Bowl 32 after rushing for three touchdowns in that game. Tragically, in the Broncos fourth game of the 1999 season, Davis tore his ACL and MCL in his right knee, causing him to miss the rest of the season. In 2000, he missed 11 more games due to injury, and then only played in eight games during the 2001 campaign season after enduring surgery on both knees. Davis was eventually forced to retire in 2002, leaving behind so many questions about what he could’ve accomplished if he hadn’t gotten hurt.

(AP Photo/Ed Reinke, File)

4. Tony Boselli, Age 29

Among NFL coaches and general managers, Tony Boselli is still viewed as one of the best left tackles the game has ever seen. During the 1990s, there seemed to be glut of great left tackles – many of whom have been inducted into the NFL Hall of Fame. Players such as Orlando Pace and Jonathan Ogden have scaled the heights of the game. Yet Tony Boselli might’ve been the best left tackle of them all, and could have likely been a Hall of Famer too, had his career not been cut short by injury. The first ever selection of the Jacksonville Jaguars expansion franchise, Boselli demonstrated remarkable athleticism for a man that stood 6’7″ and weighed 320 pounds. He was a five-time Pro Bowl selection and three-time All Pro in his short six year career, which came crashing to a halt when he injured his left shoulder. Boselli attempted a comeback with the Houston Texans a few years after tearing his shoulder up, but it was not to be. He was never healthy enough to make it onto the field and was forced to retire. Still viewed as one of the best ever in many circles.

3. Troy Aikman, Age 33

Although he was forced to retire at age 33, Troy Aikman still managed to have a Hall of Fame career during his decade as the quarterback for the Dallas Cowboys. He did, after all, win three Super Bowls. Even nearing his mid-30s, Aikman was still a solid and reliable quarterback when he got seriously hurt in the late 1990s. Aikman was already feeling the effects of all the hits he took early in his career when he began to endure back problems. He missed seven games during the 1998 and 1999 seasons due to both concussions and back problems. In the 2000 season, in what would be his final home game in Dallas, Aikman was scrambling out of bounds when he took a violent hit from Washington Redskins rookie linebacker LaVar Arrington. The impact of the hit caused him to suffer an eye popping tenth concussion. Doctors refused to clear him to play, and Aikman was forced to hang ’em up.

(AP Photo/Tsugufumi Matsumoto)

2. Gale Sayers, Age 28

Gale Sayers was a true NFL superstar in the late 1960s and early 1970s, and we can only wonder what might have been had his career lasted longer. During his first three seasons in the league, “The Kansas Comet” put up a staggering 6,401 total yards from scrimmage (rushing, receiving, and returning punts and kicks). He was named Rookie of the Year in 1965, and was named to the Pro Bowl in each of those first three seasons. Sadly, midway through his fourth season in 1969, Gale Sayers tore the ACL in his right knee. While such an injury has become common in today’s NFL, and the recovery has even become fairly routine, orthopedic surgeons at the time lacked the same technology needed to repair such an injury. Even though he was still named to Pro Bowls and All Pro teams when he returned to the NFL, Sayers was never quite the same player after the injury. When Sayers injured his other knee in 1970, his career was effectively over at the age of 28. He played in only two more games in 1971, and ended his career having played for less than four-and-a-half total seasons.

(AP Photo/File)

1. Bo Jackson, Age 28

From the famous “Bo Knows” Nike marketing campaign to his appearance in the Tecmo Super Bowl video game, NFL running back Bo Jackson was a blazing hot superstar in the NFL during the early 1990s. Playing both professional baseball and football, Jackson was a good enough athlete to be named an All-Star in two different sports. Because of his on-field success and his off-the-field endorsements, Jackson became somewhat of a cultural phenomenon – if only briefly. Shortly after the 1990 seasons, a year where he hit more than 20 home runs for the Kansas City Royals and was named to the NFL Pro Bowl, Jackson dislocated his hip while playing in the Oakland Raiders opening playoff game in January 1991. Jackson stated that he popped his hip back into the socket after the run, which actually damaged the blood vessels going to his hip. Shortly after that, he was diagnosed with avascular necrosis of the hip joint, forcing him to retire from football and then baseball a short time later Sadly, Jackson only played 38 games during four NFL seasons before calling it quits at age 28.

(AP Photo/Beth Keiser)