With apologies to basketball greats Bob Cousy and Larry Bird, Bill Russell will forever be the most important superstar ever to play for the Boston Celtics.

And with another apology, to legendary NFL quarterback Tom Brady, Russell will always be the GOAT – not just of Boston, but of excellence and winning in American sports.

The 11-time NBA champion, who passed away this weekend at the age of 88, was among the greatest ever to play the game of basketball. But his greatness was also measured by his achievements off the court – his tireless social justice activism reflecting America’s postwar evolution away from Jim Crow racial segregation as well as the struggle for civil rights and Black Power that transformed the country.

Russell’s early life was marked by the tragic death of his mother and the daily challenges of growing up in racially segregated Monroe, Louisiana, where his father was threatened with a shotgun for challenging Jim Crow-era rules that allowed Whites to be served ahead of Blacks. His mother, who passed away when he was 12, was nearly arrested once for being too elegantly dressed for a Black woman.

Russell’s family later migrated to Oakland, California, where he became a top player on his high school basketball team, followed by a star turn in college basketball, leading the University of San Francisco to two NCAA championships. In 1956, he led the US Olympic team to a basketball gold medal.

Then came the proving ground of Boston.

Russell joined the Boston Celtics in 1956, just two years after the Supreme Court’s Brown v. Board of Education decision announced the notion of “separate but equal” schooling unconstitutional. As one of few Black players on the Celtics, Russell experienced a unique kind of racial trauma.

He would remember Boston as “a flea market of racism” possessing an astonishing variety of ways to display contempt toward African Americans.

“The city had corrupt, city-hall-crony racist, brick throwing, send-‘em-back-to-Africa racist, and in the university areas, phony radical-chic racists (long before they appeared in New York),” he bitterly recalled in his memoir, “Second Wind,” written with the great author and historian Taylor Branch.

Perhaps out of defiance against the racism he encountered throughout his life, Russell became one of the country’s most visible athletes in the civil rights realm. He charged the overwhelmingly White NBA in the late 1950s with purposely excluding Black players. In 1961, after two Black Boston Celtics were denied service at a Lexington, Kentucky, restaurant before a preseason exhibition game, Russell led a boycott in which he and other Black players refused to play in the state.