Donald Arvid Nelson (born May 15, 1940), sometimes known as Nellie, is an American former National Basketball Association (NBA) player and head coach. He coached the Milwaukee Bucks, the New York Knicks, the Dallas Mavericks, and the Golden State Warriors. After an All-American career at the University of Iowa, Nelson won five NBA Championships with the Boston Celtics and had his number 19 retired by the franchise.
An innovator, Nelson is credited with, among other things, pioneering the concept of the point forward, a tactic which is frequently employed by teams at every level today. His unique brand of basketball is often referred to as Nellie Ball. He was named one of the Top 10 coaches in NBA history. On April 7, 2010, he passed Lenny Wilkens for first place on the all-time NBA wins list with his 1,333rd win. His all-time record coaching record was 1,335–1,063 (.557). Nelson was inducted into the Naismith Basketball Hall of Fame in 2012.