NBA legend Bill Russell, an 11-time NBA champion with the Boston Celtics and the first Black head coach in the league, passed away “peacefully” Sunday, according to a family statement from his verified Twitter account. He was 88.

The statement reads, “It is with a very heavy heart we would like to pass along to all of Bill’s friends, fans, & followers. Bill Russell, the most prolific winner in American sports history, passed away peacefully today at age 88, with his wife, Jeannine, by his side. Arrangements for his memorial service will be announced soon.”

The family statement continued, “Bill’s two state championships in high school offered a glimmer of the incomparable run of pure team accomplishment to come: twice an NCAA champion; captain of a gold-medal-winning US Olympic team; 11 times an NBA champion; and at the helm for two NBA championships as the first black head coach of any North American professional sports team.”

Along with his sporting achievements, Russell was one of sport’s leading civil rights activists and marched alongside Martin Luther King Jr. when he gave his “I Have a Dream” speech in 1963. He also supported iconic boxer Muhammad Ali’s opposition to being drafted into military service.

Russell won 11 championships with the Celtics, including eight straight from 1959 to 1966. He was a five-time NBA MVP and a 12-time All-Star. As a coach for the Celtics, he led Boston to two titles, becoming the first Black head coach to win an NBA championship.

Russell was born in rural Louisiana in 1934. At eight years old, his family moved to Oakland, California, for better job opportunities. At McClymonds High School in Oakland, Russell became a senior starter on the basketball team, already emphasizing defense and rebounding. A former University of San Francisco basketball player, Hal DeJulio, who scouted for his alma mater, recognized Russell’s potential and recommended him to the coach, Phil Woolpert.

The Boston Celtics drafted Russell in 1956 after trading other players, and his impact was immediately felt. The Celtics won a title in his rookie year, and he became the league’s first African American superstar, though not its first Black player, who was Earl Lloyd in 1956. During his career, Russell supported the American civil rights movement, spoke out against the Vietnam War, and did much that, had it come from any lesser athlete, would have caused immediate controversy. However, the Celtics kept winning, and he remained the engine that made them go.

Fellow NBA legend Michael Jordan, widely considered the greatest basketball player of all time, said, “Bill Russell was a pioneer; as a player, as a champion, as the NBA’s first Black head coach, and as an activist. He paved the way and set an example for every Black player who came into the league after him, including me. The world has lost a legend. My condolences to his family, and may he rest in peace.”

Russell stood for more than basketball. He used his platform to advocate for messages that meant something to him and those in need. He rose above adversity and stayed true to his beliefs.