Don Nelson, second-winningest NBA coach who won 5 titles as a Celtics player, dies at 86By Canadian Press on August 9, 2026. Don Nelson, the second-winningest coach in NBA history who won five championships as a player with the Boston Celtics, died Sunday. Nelson’s death was announced by the Golden State Warriors, one of the teams he coached. His fast-paced offenses were probably best on display with Golden State in the “Run TMC” era featuring future Hall of Famers Tim Hardaway, Mitch Richmond and Chris Mullin. In his final season as a coach, Nelson mentored rookie Stephen Curry in 2009-10.