Background and college
Born December 10, 1938 in Rocky Mount, North Carolina, Mathis went to Clemson, where he starred for the Tigers from 1957-59. He played many positions throughout his three-year career at Clemson. He was a halfback, punter, and a defensive back. He was on the 1958 team that lost to number-one ranked LSU in the 1959 Sugar bowl as well as the 1959 team that won the Bluebonnet Bowl. As a running back he had 975 yards in 216 carries, 34 catches for 602 yards, and seven touchdowns. As a defensive back he had two interceptions and as a punter he averaged 35.8 yards a punt.
Mathis would be named to the Clemson University Hall of Fame, South Carolina Hall of Fame, and the Georgia Hall of Fame.
As a Titan/Jet
One of four Titans who would remain with the Jets to play in and win a World Championship game, Mathis was signed as an undrafted free agent in 1960. In 1961, Mathis had his best season, leading the American Football League in carries in 1961 while finishing second in rushing yards and was selected by his peers to the Sporting News 1961 AFL All-League team. He was also named an AFL Eastern Division All-Star. In the third game of the season, against the Boston Patriots, Mathis fractured his collarbone, but managed to play in all the remaining games of the season. 1962 was the only season Mathis failed to play a full season, missing three games. In 1963, Mathis was named AFL Eastern All Star for the second time.
Even after the arrival of Emerson Boozer and Matt Snell in the mid sixties, Mathis still saw plenty of playing time, being an ever present until the end of his career. He also played in Super Bowl III, with three rushes for two yards, and three receptions for twenty yards. Mathis then announced his retirement, but was talked into coming back for one more season as the Jets needed another blocking back. However, after the Jets lost to Kansas City in the 1969 playoffs, Mathis would retire, having spent his entire career with the team. After Snell suffered a season ending Achilles tendon injury in October 1970, Mathis was lured out of retirement yet again. However before Mathis would play a game, the Jets signed Chuck Mercein, so Mathis retired again, this time for good. His 3,589 rushing yards ranks him seventh on the all time Jets list.
After the NFL
Mathis went on to work in securities after his retirement.
Mathis is one of twenty players who were in the AFL for its entire ten year existence, and seven players who played their entire AFL careers for one franchise, and was named to the AFL Hall of Fame.