Bill Russell, one of basketball's legendary players, has died at age 88. 

The announcement was posted on his verified Twitter account.

Russell won more NBA titles than any player in history.

As a five-time league MVP, he changed the game, making shot-blocking a key component on defense

And he was a Black athlete who spoke out against racial injustice when it was not as common as it is today.

In a 2013 interview for the Civil Rights History Project, Russell said his mother's message to her teary son changed his life.

One day when Bill Russell was 9, he was outside his apartment in the projects in Oakland, Calif.

 Five boys ran by and one slapped him in the face. He and his mother went looking for the group, and when they found them, young Bill expected mom justice.

Russell certainly did on the basketball court — where he blossomed late but ended up revolutionizing the game.