George Matthew Karl (born May 12 1951, in Penn Hills, Pittsburgh, Pennsylvania) is a retired American National Basketball Association (NBA) and American Basketball Association (ABA) player and current head coach of the Denver Nuggets. Karl is currently 12th on the all-time win list for coaches in the NBA. After a college career at the University of North Carolina he signed with the ABA's San Antonio Spurs in 1973. When the Spurs joined the NBA in 1976, Karl began his two-year NBA playing career. After his playing career, Karl became an assistant coach for the Spurs. Karl then moved on to the Continental Basketball Association (CBA) as head coach of the Montana Golden Nuggets (Great Falls). As coach of the Golden Nuggets, Karl won CBA Coach of the Year twice, in 1981 and 1983.

In 1984, Karl became the head coach of the NBA's Cleveland Cavaliers until he was fired in 1986. He later coached the Golden State Warriors until 1988, achieving a winning record and a first-round playoff upset in his first season, before being fired after a terrible start to the 1987-88 campaign. He coached briefly in the 1989 season for the Utah Jazz as an assistant. After being fired from Jerry Sloan's staff in Salt Lake City, Karl returned to the CBA as coach of the Albany Patroons, winning the coach of the year award in 1991.

Karl returned to the NBA as coach of the Seattle SuperSonics from 1991-1998, leading them to the NBA Finals in 1996 where they lost to the Chicago Bulls in six games. In all seven of his seasons in Seattle, the team made the postseason, winning three division titles, and eclipsing the 50-win mark in every year that he was the full-time coach. The biggest disappointment of Karl's tenure in Seattle came in 1994, when the 63-win Sonics were upset in the first round by the Denver Nuggets, marking the first time in NBA history that an eight seed defeated a number one seed.

In 1998, Karl moved to the Milwaukee Bucks as head coach, lured by an excellent contract. He rebuilt a struggling team in his first three years, steadily increasing win totals, and guiding the team within one game of the NBA Finals in 2001. However, his team collapsed down the stretch in 2002, falling from the number one spot in the Eastern Conference in January to a season that ended out of the playoffs. He was fired after another underachieving season in 2003, where his team made the playoffs with a win total of just over the .500 mark.

He coached the US national team in the 2002 FIBA World Championship.

He returned to the NBA in 2005 when he became head coach of the Nuggets, taking over from interim head coach Michael Cooper on January 27 and leading the team on an incredible run to the postseason.

He also spent two years in Spain coaching the Real Madrid basketball team in 1989-90 and 1991-92 .

On July 27, the Nuggets announced that Karl had prostate cancer. He has enjoyed a resurrection of his career with the Denver Nuggets, guiding them to an unprecedented 32-8 record in the second half of the 2004-05 season.

Karl's son Coby is a reserve guard for the Los Angeles Lakers, after a career as starting point guard for Boise State University. Coby came out for the 2006 NBA Draft after a bout with thyroid cancer, but withdrew his name before the draft and returned to Boise State for his senior year.

On December 28, 2006, Karl became just the 12th coach in NBA history to reach the 800-win mark when his Denver Nuggets defeated the Seattle SuperSonics 112-98.