(NEXSTAR) — Bill Russell, one of the greatest NBA players in history, has passed away at age 88, his family announced Sunday.

Russell, called “the most prolific winner in American sports history” by his family, was an 11-time NBA champion, captain of a gold-medal-winning U.S. Olympic team, and the first Black head coach of any North American professional sports team.

Born on Feb. 12, 1934, in Monroe, Louisiana, Russell, and his family later moved to California. He attended high school in Oakland and led the University of San Francisco to NCAA championships in 1955 and 1956. He also won a gold medal at the 1956 Olympics.

Russell was drafted in the first round of the 1956 NBA draft by the St. Louis Hawks but was soon traded to the Boston Celtics. He spent 13 years in Boston — 10 as a player and three as a coach. In that time, the team won 11 championships.

He was the first black head coach in NBA history when he became player-coach in 1966. He retired after the 1969 NBA finals but later spent four years as a coach and general manager of the Seattle SuperSonics and a half-season as a coach for the Sacramento Kings.

The Hall of Famer was named Most Valuable Player five times and was a 12-time All-Star. In 1980, Russell was voted the greatest player in NBA history by basketball writers. He remains the sport’s most prolific winner and an archetype of selflessness who won with defense and rebounding while leaving the scoring to others. Often, that meant Wilt Chamberlain, the only player of the era who was a worthy rival for Russell.

Russell’s No. 6 jersey was retired by the Celtics in 1972. He earned spots on the NBA’s 25th anniversary all-time team in 1970 and 35th-anniversary team in 1980. In 1996, he was hailed as one of the NBA’s 50 greatest players. In 2009, the MVP trophy of the NBA Finals was named in his honor.

In 2013, a statue was unveiled on Boston’s City Hall Plaza of Russell surrounded by blocks of granite with quotes on leadership and character. Russell was inducted into the Basketball Hall of Fame in 1975 but did not attend the ceremony, saying he should not have been the first African American elected. (Chuck Cooper, the NBA’s first Black player, was his choice.)

In 2019, Russell accepted his Hall of Fame ring in a private gathering. “I felt others before me should have had that honor,” he tweeted. “Good to see progress.”

“But for all the winning, Bill’s understanding of the struggle is what illuminated his life,” Russell’s family said in a statement. “From boycotting a 1961 exhibition game to [unmasking] too-long-tolerated discrimination to leading Mississippi’s first integrated basketball camp in the combustible wake of Medgar Evans’ assassination, to decades of activism ultimately recognized by his receipt of the Presidential Medal of Freedom in 2010, Bill called out injustice with an unforgiving candor that he intended would disrupt the status quo, and with a powerful example that, though never his humble intention, will forever inspire teamwork, selflessness, and thoughtful change.”

Russell was at the March on Washington in 1963, when Martin Luther King Jr. gave his “I Have a Dream” speech, and he backed Muhammad Ali when the boxer was pilloried for refusing induction into the military draft.

In 2011, President Barack Obama awarded Russell the Medal of Freedom.

“Bill Russell, the man, is someone who stood up for the rights and dignity of all men,” Obama said at the ceremony. “When a restaurant refused to serve the Black Celtics, he refused to play in the scheduled game. He endured insults and vandalism, but he kept on focusing on making the teammates who he loved better players and made possible the success of so many who would follow.”

NBA Commissioner Adam Silver said in a statement Sunday that Russell was “the greatest champion in all of team sports.”

“Bill stood for something much bigger than sports: the values of equality, respect, and inclusion that he stamped into the DNA of our league. At the height of his athletic career, Bill advocated vigorously for civil rights and social justice, a legacy he passed down to generations of NBA players who followed in his footsteps,” Silver said. “Through the taunts, threats, and unthinkable adversity, Bill rose above it all and remained true to his belief that everyone deserves to be treated with dignity.

Russell “passed away peacefully” with his wife, Jeannine, by his side on Sunday. His cause of death has not yet been released.

His family said that arrangements for Russell’s memorial service will be announced in the coming days.

The Associated Press contributed to this report.