Bill Russell won eleven NBA titles during his career in the 1950s and '60s and was named the league's Most Valuable Player five times.
In 1956 he was captain of the USA team that won the Olympics in Melbourne.
Russell becomes the first player to have his jersey retired in the entire NBA.
He was also the NBA's first black coach and a pioneer in diversity work and, above all, black rights.
He occasionally joined Martin Luther King during his political career.
Russell will permeate the entire NBA
Players who currently wear number 6, LeBron James being the most famous, may continue to do so but the number will not be allowed to be used by new players in the future.
In the coming season, each team will have a small commemorative detail around Russell on their jerseys and all scoreboards will have a small six as a logo to honor Russell.
"Permanently retiring the number 6 throughout the NBA ensures that Bill's outstanding career will always be remembered," said NBA president Adam Silver.
Russell played his entire career with the Boston Celtics, where his number was already retired, something that happened back in 1972.
He was inducted into the Basketball Hall of Fame in 1975 and received the Presidential Medal of Freedom by Barack Obama in 2010.