(WTVO) — Bill Russell, one of the most prolific players in NBA history, has passed away at 88.

The news came from Russell’s Twitter early Sunday afternoon. Russell won 11 NBA championships over his 13 years as a Center for the Boston Celtics, as well as being named a two-time NCAA champion and captain of the gold-medal-winning US Olympic team.

Russell also made history as the first Black head coach of any North American professional sports team, leading the Celtics to two NBA championships. In 2009, the award for the NBA finals most valuable player was renamed as the “Bill Russel NBA Finals Most Valuable Player Award” in honor of the two-time Hall of Famer.

A champion on and off the court, Russell was a strong voice for civil rights. From boycotting a 1961 exhibition game to unmask discrimination to leading Mississippi’s first integrated basketball camp, decades of activism lead to Russell receiving a Presidential Medal of Freedom in 2010.

Bill leaves behind his wife Jeannine and three kids.