The number 6 is not entirely forbidden in the National Basketball Association, but it holds a unique status because the league officially retired the number league-wide in honor of legendary Boston Celtics icon and civil rights pioneer Bill Russell following his passing. Any player who was actively wearing number 6 prior to that historic announcement was permitted to keep wearing it under a grandfather clause, but no new players across any franchise are allowed to select or wear the number 6, cementing his unprecedented legacy across the sport.