Don Nelson, a Hall of Fame coach and former Boston Celtics star, has died at 86. He died on Sunday at an assisted living facility in Frisco, Texas. Nelson was one of the most successful coaches in NBA history. His long career helped shape the game in new ways. He coached the Milwaukee Bucks, Golden State Warriors and Dallas Mavericks. He also had a short spell with the New York Knicks. Nelson spent 31 years as an NBA head coach. He led teams that became strong forces in the league. His teams often played in a bold and free style. He was known for trying new ideas and finding ways to use players in different roles. His work on the bench made him one of the league’s most respected coaches. He was also known as Nellie. His coaching career lasted for decades and became a key part of his place in NBA history. Nelson’s health had worsened after he suffered a stroke about three weeks before his death. His granddaughter, Christie Nelson Armstrong, confirmed the cause of his recent decline. His NBA career was unusual from the start. Nelson was not a large or fast player. He played small forward and lacked the size and speed that many teams wanted. He was twice waived by NBA teams. Yet he kept working toward a place in the league. His chance came with the Celtics in 1965. Boston soon found great value in him. Nelson became part of one of the strongest teams in NBA history. He won five NBA titles as a player with the Celtics. He was often used as a reserve. His shooting gave Boston a major boost when he entered games. He became known for his strong jump shot and his skill at changing the flow of a game. His best-known moment as a player came in the 1969 NBA Finals. Nelson hit a key basket against the Los Angeles Lakers. The shot became one of the most famous moments of his playing career. After his playing days ended, Nelson moved into coaching. His new role gave him a chance to show his deep view of the game. As a coach, Nelson did not always follow old rules. He looked for new ways to create space and gain an edge. He was willing to change his plans when he saw a better way to use his team. That approach helped build his reputation as an inventive coach. He was not afraid to test ideas that were different from the usual style of the time. Nelson had long runs with the Bucks, Warriors and Mavericks. He helped each team reach a higher level. His teams became known for smart play and creative plans. His time with Golden State was especially linked to his bold approach. He helped create a style that used smaller lineups and placed new demands on bigger players. That style later became a major part of the modern NBA game. Coaches across the league began to use more space, speed and shooting. Nelson’s ideas helped push that change. His career also showed that success can come from thinking differently. He had already overcome doubts about his size as a player. As a coach, he again built his career by trusting his own ideas. Nelson finished his career as one of the NBA’s winningest coaches. His long service and success earned him a place in the Basketball Hall of Fame. His legacy reaches beyond wins and losses. He helped change how coaches viewed players, lineups and team play. He gave smaller players more value and showed how a team could use speed and skill to create problems. Nelson’s career also linked two different eras of the NBA. He was a champion as a player in Boston. Later, he became a coach who helped shape a new style of basketball. His death closes a career that lasted almost 50 years. His work as a player earned five NBA rings. His work as a coach left a deeper mark on the game. For many in basketball, the Don Nelson coaching legacy will remain tied to one simple idea. The game can change when a coach is willing to think in a new way.