James Larnell "Shack" Harris (born July 20, 1947) is an American former professional football player and executive. He played as a quarterback in the American Football League (AFL) and the National Football League (NFL) with the Buffalo Bills, Los Angeles Rams, and San Diego Chargers. In 1969, Harris became the first Black quarterback to start a season opener for the either the AFL or NFL, and in 1974, he became the first Black quarterback to start an NFL playoff game. After his playing career, Harris worked in the front office for the Detroit Lions, Jacksonville Jaguars, New York Jets, Tampa Bay Buccaneers, and Baltimore Ravens, where he was a part of the Super Bowl XXXV-winning team.

Harris grew up in Monroe, Louisiana. He is the son of Lula B. and father, Nashall Harris, Sr., a furniture maker and minister. His older sister is Lucille Richards, and his older brother is Nashall Harris, Jr., who was called "Meshach" that morphed into "Shack." James, the younger brother, was called "Little Shack." When his older brother left home to join the Army, and James grew to six feet-four inches, the family dropped the "Little" from his nickname to just "Shack."

Harris attended Carroll High in Monroe, where he led the football team to a Louisiana state championship in his sophomore year, and two perfect seasons. He was twice named to the all state football team. A straight-A student, Harris also played on the school's baseball team.

Harris played college football for HBCU Grambling State University from 1965 to 1968, and as a three-year starter led the Tigers to a 24–5–1 record. Coached by legendary Grambling coach Eddie Robinson, Harris and his teammates won or shared all four Southwestern Athletic Conference (SWAC) titles during his college career. Harris was specifically trained as a prototypical pocket-passer-by Robinson and broke numerous passing records at Grambling. In 1967, he was named MVP of the Orange Blossom Classic.

In 2023, Grambling renamed its football field, the "James "Shack" Harris and Doug Williams Field at Eddie G. Robinson Memorial Stadium," to honor the university's most prominent football alumni.

Harris was drafted in the eighth round of the 1969 Common draft by the American Football League's Buffalo Bills, and would soon join fellow rookie O. J. Simpson in the starting backfield.

Continuing the American Football League's more liberal (than the NFL's) personnel policies, the Bills made Harris the first black player to start a season at quarterback in the history of pro football.

Harris was also just the second black player in the modern era to start in any game as quarterback for a professional football team. Wide receiver Marlin Briscoe, of the AFL's Denver Broncos, had been the first to start a game at quarterback in 1968, and a few of Harris's completions in 1969 went to Briscoe, who, by that time, had been traded to the Bills and had been converted to the position of receiver. In the first game of the season against the defending champion New York Jets, he went 3-of-12 for 74 yards with an interception while making a run for six yards before being replaced by Jack Kemp (playing his final season) as the Bills were trounced 33–19. It was his only start for the season, and Harris threw just 24 total passes combined in the other three games he appeared in as the team went 4–10. He scored his first touchdown on a throw to Haven Moses for 39 yards in a 50–21 loss to the Oakland Raiders. He made no starts in 1970, going 24-of-50 for 338 yards with three touchdowns and four interceptions in a year where the Bills went 3–10–1 while using newly drafted Dennis Shaw as their main starter. For his third and last year with the team, he made two starts (both losses) with seven appearances, going 51-of-103 for 512 total yards with one touchdown and six interceptions. After three years with the Bills, Harris was released by the team and signed by the Los Angeles Rams in 1972.