Bill Russell, one of the greatest basketball players of all time who led the charge on and off the court, has died, his family announced Sunday. He was 88.

Russell’s family said in a statement that he passed away "peacefully" with his wife by his side. It was unclear how Russell died.

"It is with a very heavy heart we would like to pass along to all of Bill’s friends, fans & followers," the statement started.

"Bill Russell, the most prolific winner in American sports history, passed away peacefully today at age 88, with his wife, Jeannie, by his side. Arrangements for his memorial service will be announced soon.