Don Nelson, one of the most influential coaches in NBA history and a five-time champion as a Boston Celtics player, has died at the age of 86.

Nelson’s family said he died peacefully on Sunday, August 9, surrounded by family members. The Golden State Warriors, one of the teams he coached, subsequently confirmed his death. No official cause was immediately disclosed.

Known across basketball as “Nellie,” Nelson completed a 31-year coaching career with 1,335 regular-season victories. That places him second on the NBA’s all-time coaching wins list behind Gregg Popovich.

Five Championships With Boston Celtics

Before becoming a coach, Nelson played 14 seasons in the NBA, including 11 with the Boston Celtics.

He was part of five Celtics championship-winning teams and became known as a dependable and intelligent player under legendary coach Red Auerbach. Boston later retired his No. 19 jersey.

Nelson moved into coaching after his playing career and led the Milwaukee Bucks, Golden State Warriors, New York Knicks and Dallas Mavericks.

He was named NBA Coach of the Year three times and reached the playoffs in 18 of his 31 seasons as a head coach.

Architect of Modern NBA Basketball

Nelson became famous for experimenting with smaller and faster line-ups, using versatile players in unconventional positions and prioritising attacking basketball.

Several tactical ideas associated with him later became common across the NBA, earning him recognition as one of the architects of the modern game.

He helped turn the Milwaukee Bucks into consistent contenders and later played an important role in developing the Dallas Mavericks around Dirk Nowitzki and Steve Nash.

Nelson also supported Stephen Curry during Curry’s rookie season with Golden State.

Historic ‘’ Playoff Victory

One of Nelson’s most memorable coaching achievements came in 2007, when his eighth-seeded Golden State Warriors defeated the top-seeded Dallas Mavericks in the opening round of the NBA playoffs.

The result remains one of the biggest upsets in NBA playoff history and became the defining moment of Golden State’s “We Believe” team.

Nelson retired from coaching in 2010. He was inducted into the Naismith Memorial Basketball Hall of Fame in 2012 and received the Chuck Daly Lifetime Achievement Award in 2025.

NBA Commissioner Adam Silver, Stephen Curry, Dirk Nowitzki and Nelson’s former teams were among those paying tribute to his influence on basketball.