NBA legend Bill Russell, the cornerstone of a Boston Celtics dynasty that won 11 titles and a powerful voice for social justice, has died at the age of 88, his family announced Sunday.

"Bill Russell, the most prolific winner in American sports history, passed away peacefully today at age 88, with his wife, Jeannine, by his side," said a statement posted on his social media accounts.

An announcement… pic.twitter.com/KMJ7pG4R5Z

— TheBillRussell (@RealBillRussell) July 31, 2022

The first Black coach in the NBA

Russell's 11 titles with the Celtics included eight in a row from 1959-1966. Today's NBA Finals MVP award is named for him.

He averaged 15.1 points and 22.5 rebounds per game for his career, building a famed rivalry with Wilt Chamberlain in the 1960s.

He would become the first Black coach in the NBA and the first Black player inducted into the Basketball Hall of Fame in 1975.

A giant in the fight for civil rights

Off the court, Russell was a giant in the fight for civil rights, receiving the Presidential Medal of Freedom, the United States' highest civilian honor, from then-President Barack Obama in 2011.

"But for all the winning, Bill's understanding of the struggle is what illuminated his life," Sunday's statement on his Twitter page said.

The statement pointed out that "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."

"The greatest champion"

NBA Commissioner Adam Silver called Russell "the greatest champion in all of team sports."

In a statement, Silver pointed out that "Bill stood for something much bigger than sports: the values of equality, respect and inclusion that he stamped into the DNA of our league."

NBA Commissioner Adam Silver's statement regarding the passing of Bill Russell. pic.twitter.com/3BcZDnKjxK

— NBA (@NBA) July 31, 2022

"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," he added.

"Making things better in the Black community"

On his part, Los Angeles Laker legend, Magic Johnson, said that Russell was "one of the first athletes on the front line fighting for social justice, equity, equality, and civil rights."

"That's why I admired and loved him so much. Over the course of our friendship, he always reminded me about making things better in the Black community," Johnson said in a statement.