With time winding down to the Jan. 15 deadline for college football players to declare themselves eligible for the NFL draft, it's the perfect time for a history lesson on the best student-athletes to depart school early to head to the pros.
Texas A&M great and 2012 Heisman Trophy winner Johnny Manziel still hasn't made his announcement, though a spot on this list will likely be made if he leaves College Station early.
Until then, click on for the list of the 10 best players to leave school early for the NFL draft.
The primary judging factor is the player's collegiate career, seconded by his time in the NFL. Other factors, such as program and historical impact, also play a role in the rankings.
Note: Stats via Sports-Reference.com, unless otherwise noted.
Desmond Howard won the 1991 Heisman Trophy in one of the biggest landslides in the award's history.
Howard was a phenomenal playmaker at Michigan and will go down as one of the best all-purpose talents in college football history.
His junior season, Howard notched 19 receiving touchdowns, two rushing touchdowns and brought back a punt and a kick for a score. He had nearly 2,000 all-purpose yards when he took the Heisman, prompting him to be drafted No. 4 overall.
As a pro, his primary use was in the return game, which led him to finish with more than 12,000 all-purpose yards for his career.
He wasn't as great of a pro as some others on this list, but he was an iconic collegiate star in Ann Arbor.
LSU has a penchant for churning out defensive backs, and Patrick Peterson may be the best in that lineage.
He captured the Bednarik Award, given to the nation's best defensive player, in 2010 and was also an exceptional return man. His junior year, he tallied 1,350 return yards and intercepted four passes.
He was a lockdown corner and went on to do much of the same at the professional level.
After declaring early for the draft, he was selected fifth overall by the Arizona Cardinals. He has been named to the Pro Bowl three times and is a two-time All-Pro selection.
Defensive backs don't always garner the most attention, but Peterson is definitely deserving of praise.
Andre Ware became the first black quarterback to ever win the Heisman Trophy after a remarkable run at Houston.
His junior campaign was absolutely outstanding, as he tallied nearly 4,700 passing yards and 46 touchdowns as the Cougars finished 9-2.
He beat out several talented players, including Emmitt Smith, Major Harris and Ty Detmer to win the Heisman in 1989. He left school early and was taken seventh overall by the Detroit Lions.
His professional career was short-lived, as he never started more than three games in any of his four seasons in Detroit.
While his pro career wasn't much to write home about, it doesn't take away from his outstanding career at Houston or his historic Heisman win.
Before Robert Griffin III came to Baylor, the Bears hadn't posted a winning season in more than a decade and were locked in the bottom of the Big 12 cellar.
However, RGIII was the key to climbing out. By the time he left Waco, he was the school's first Heisman winner and delivered it a 10-win season for the first time since 1980.
He had a decent freshman campaign, then took a medical redshirt as a sophomore after tearing his ACL in the third game of the season. The future No. 2 overall pick came back strong as a redshirt sophomore then exploded into the national picture as a junior.
With Baylor winning games and suddenly in the national spotlight, Griffin neared 5,000 yards rushing and passing and won the 2011 Heisman Trophy.
He has already shown signs of being a star at the professional level, though an injury slowed him in his second year with the Washington Redskins.
Still, with Baylor showing some staying power in the Big 12, it's tough to pick one player who has had as much impact on a program as RGIII did for the Bears.
Few players in college football history were as electric as USC legend Reggie Bush.
His 2005 season was one of the best individual campaigns in history. He tallied more than 2,800 all-purpose yards and 19 touchdowns, making him an easy choice for the Heisman Trophy, even though there were several other incredible players in the running.
He later vacated that award and season, but that doesn't erase his accomplishments from history.
Bush has gone on to have a solid NFL career, though he hasn't had nearly as much of an impact at the professional level.
Despite those mixed results, Bush is still one of the greatest to ever play college football.
Former San Diego State star Marshall Faulk is regarded as one of the biggest Heisman Trophy snubs in history.
He was beaten out by Miami (Fla.)'s Gino Torretta despite accounting for nearly 2,500 yards and 24 touchdowns between rushing and receiving.
While a place on this list won't make up for the missing Heisman, it is certainly deserved.
Faulk was drafted No. 2 overall after departing following his junior season. He would go on to be named to seven Pro Bowls while with the Indianapolis Colts and St. Louis Rams.
A back who excelled at college and in the pros, Faulk is one of the greatest of all time.
There might not be a player who had as much impact on a team in just one season as Auburn's Cam Newton.
Newton's career began at Florida, where he spent one season as a redshirt and another as a backup before transferring out to Blinn College. In one year at Blinn, he captured the junior college national title and headed off to Auburn for his redshirt junior campaign.
He immediately became a star for the Tigers, leading them to an SEC and BCS title, winning the Heisman Trophy along the way.
After accounting for more than 4,300 yards and 50 touchdowns, it was an easy decision for Newton to declare for the NFL draft, where he was taken No. 1 overall by the Carolina Panthers.
His professional career has been up and down thus far, but he guided Carolina to the NFC South crown in 2013.
It takes a special person to beat Peyton Manning heads-up at anything.
Still the only primary defensive player ever to win the Heisman Trophy, Michigan great Charles Woodson edged Manning to win the award in 1997.
He also saw some time as an all-purpose offensive player and returner, but his lockdown coverage and seven interceptions paved the way for him to take the honor.
He left Ann Arbor early after tallying 18 career interceptions and went on to be one of the best defensive backs in NFL history. He has been named All-Pro seven times and is still in the league 16 seasons after being drafted fourth overall by the Oakland Raiders.
Few players have that kind of longevity, one of several reasons Woodson is one of the best underclassmen to ever enter the draft.
Emmitt Smith is best known as the NFL's all-time leading rusher, but he also had a great career as a Florida Gator.
He nearly touched 4,000 yards in three seasons in Gainesville, despite playing just nine games as a sophomore.
As a junior, he tallied 1,599 rushing yards and 14 touchdowns, prompting him to forego his senior season and head to the draft.
After being taken 17th by the Dallas Cowboys, Smith would go on to have the best career of any running back ever. He finished with 4,409 attempts, 18,355 yards and 164 touchdowns—all records that might never be broken.
What else is there to say?
Former Oklahoma State legend Barry Sanders takes the top spot on this list for several reasons.
Firstly, it was he who set the precedent as the first non-senior to ever be declared eligible for the draft in 1989.
But he is mostly at No. 1 because he is one of the greatest running backs ever at both the collegiate and professional level. Many running backs are said to be "like Barry Sanders," but there is still only one true Barry Sanders (disregarding his son, Stanford running back Barry Sanders Jr.).
He still reigns as college football's single-season rushing king after his 2,628-yard campaign in 1988. That season won him the Heisman Trophy by a landslide. He went on to go to 10 Pro Bowls and win four rushing titles in 10 seasons with the Detroit Lions.
No other player on this list had the kind of production and impact on the game that Sanders did.