Boston Retired Nelson's No. 19 Jersey in 1978. He Finished His Playing Career With 1,053 Regular-season Games and 10,898 Points

He became a standout forward at Rock Island High School and the University of Iowa before entering the NBA as the 17th pick of the 1962 draft. Nelson played one season for the Chicago Zephyrs, and two with the Los Angeles Lakers, before joining the Boston Celtics in 1965. With Boston, Nelson found his place as a reliable forward and reserve on a dynasty. He played 11 seasons for the Celtics, averaging 11.4 points and 5.2 rebounds, and won five championships.

Boston retired Nelson's No. 19 jersey in 1978. He finished his playing career with 1,053 regular-season games and 10,898 points. Nelson moved immediately into coaching, joining the Milwaukee Bucks as an assistant in 1976. He became head coach 15 games into the season and later added general manager to his responsibilities. Over 11 seasons in Milwaukee, Nelson's teams won seven consecutive Central Division titles and established the principles that would define his career: speed, shooting and an unwillingness to accept traditional positions.

Nelson's signature offense became known as "Nellie Ball, defined by smaller, versatile lineups. He won the NBA Coach of the Year award three times, in 1983, 1985 and 1992. He also coached the United States to the 1994 FIBA World Championship, winning a gold medal, and was named among the NBA's 10 greatest coaches in 1996. After leaving Milwaukee, Nelson coached the Golden State Warriors, New York Knicks and Dallas Mavericks before returning to Golden State for a final stint. In Dallas, he helped acquire Dirk Nowitzki and Steve Nash, laying the foundation for a franchise turnaround.

With the Warriors, Nelson's teams included the high-scoring "Run TMC" group (led by Tim Hardaway, Mitch Richmond and Chris Mullin). In 2007, he coached the eighth-seeded team that upset his former Mavericks in one of the NBA's most memorable playoff upsets. Nelson finished his 31-season coaching career with a 1,335-1,063 regular-season record, second all-time in NBA victories, and 18 playoff appearances. He never reached the NBA Finals as a coach but was inducted into the Basketball Hall of Fame in 2012. "RIP Nellie, former Mavericks principal owner Mark Cuban wrote on Twitter/X.