Bill Russell, a former Boston Celtics player who led a squad to 11 NBA titles and was the league's first black coach, passed away on Sunday at the age of 88. He was one of the greatest champions and models in the history of sports.

According to a statement issued on his official Twitter account, Russell, who was also vocal about civil rights, passed away peacefully with his wife Jeannine at his side. The family did not provide a cause of death.

“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 said in a statement.”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.”

The 1960s Boston Celtics dynasty was built around Bill Russell. He was known as an exceptional shot blocker who redefined NBA defenses for all time. The long-limbed center grabbed 21,620 career rebounds for an average of 22.5 per game. In fact, he led the league in rebounding in four different seasons. He was a 12-time All-Star and five-time NBA Most Valuable Player. He had 51 boards in one game, 49 in two others, and 1,000 or more boards for 12 straight seasons.

Despite having so many individual accolades, Russell's emphasis on teamwork ultimately defined his career. As such, his 13 seasons and 11 titles with the famous Celtics were his finest accomplishments. He was widely regarded as the best player in NBA history up until the rise of Michael Jordan in the 1980s and 1990s.

On February 12, 1934, William Felton Russell was born in Monroe, Louisiana. He attended Oakland's McClymonds High School. On the basketball team at McClymonds, he was an awkward, mediocre center, but because of his stature, he was given a scholarship to play at the University of San Francisco, where he excelled. He was drafted by the St. Louis Hawks in 1956 and traded to the Boston Celtics for Ed Macauley and Cliff Hagan.

And so began a career that would go down as one of the finest among all professional sports.

Ten greatest moments of Bill Russell's career

10. The NBA Named the Finals MVP Trophy after Him

Due to the fact that the Finals MVP award wasn't created until Jerry West won it against Bill Russell's Celtics in his final season, Russell never received one himself.

Russell was one of the best postseason players in the league. He also owns the NBA Finals rebounding record with 29.5 rebounds per game in 1959.

Russell was recognized by the league during the 2009 All-Star Game by having his name added to the Finals MVP award. He would later give it to Kobe Bryant in June of that same year.

9. Averaging 20 Rebounds Per Game in a Season

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During his second season in the league (1957–1958) Russell averaged 20.0 rebounds per game for the first time. That year, while guiding the Celtics to the NBA's best record, he also received his first MVP award.

It turned out to be the first among many dominant years for Russell. The next nine seasons in a row saw the 6'10 big man average 20 or more boards each game.

8. Russell Gets Traded to the Celtics

Red Auerbach made one of the most dramatic transactions in the NBA's history when the Boston Celtics traded for Bill Russell. Auerbach wanted to get a player who could shore up their interior defense, and Russell was their guy.

The St. Louis Hawks took Russell with the second overall pick in the 1956 Draft. The Celtics sent the Hawks star center Ed Macauley and the rights to Cliff Hagan in exchange for Russell's rights.

In the next two seasons, Macauley and Hagan would guide the Hawks to their first two NBA Finals trips, including the team's first championship in 1958.

Russell, however, would do so much more for the Celtics. Objectively speaking, it was a bountiful trade for both teams. Historically speaking, though, Boston obviously got the better end of the deal.

7. Won an Olympic Gold Medal in 1956

Basketball was largely an American sport in 1956, and many felt that the standard of international play was considerably below the NBA.

Having said that, Russel didn't have a Dream-Team-esque supporting cast during the 1956 Olympic Games. He captained the Americans to an unbeaten gold medal run. They won all eight of their assignments, outscoring their opponents by a margin of slightly over 50 points per game.

Russell played alongside another future Celtic in K.C. Jones.

6. Receiving the Presidential Medal Of Freedom in 2011

This is one of the highest honors any American can get, though it is not really based on Russell's on-court prowess.

Still, Russell is the first basketball player to get the highest civilian honor in the country. In recognizing him, President Obama emphasized both his illustrious basketball career and civil rights advocacy, which included a march with Dr. Martin Luther King, Jr.

5. First African-American Player in the Basketball Hall Of Fame

Even though Russell joined the Celtics six seasons after Earl Lloyd integrated the NBA and almost ten years after Jackie Robinson integrated baseball, racial issues and tensions were still very significant issues in 1956.

Russell overcame discriminatory challenges that harmed his relationship with Boston and its supporters in order to become one of the NBA's most renowned and respected players and the coach of its best team.

That was a big reason — in addition to all his on-court accomplishments — why in 1975, he was admitted to the Hall of Fame.

4. First Player To Reach 50 Rebounds In 1 Game

Russell accomplished this mind-boggling feat during a 1960 game against the Syracuse Nationals (now the Philadelphia 76ers). The only player to surpass Russell's total was Wilt Chamberlain, who owns the league record with 55 rebounds in a single game.

In addition to Russell and Chamberlain, just two other players have reached or breached the 40-rebound barrier. In contrast, Russell recorded 40+ rebounds in a game eight different times. If that's not crazy, then nothing is.

3. 5-Time NBA MVP

Only eight times in the 55-year history of the NBA MVP award have players who averaged less than 20 points per game received it.

Of those eight times, Bill Russell received five.

Despite not being 7'0 tall, Russell was one of the best rebounders and shot blockers the game had ever seen. He was to the defensive end what Michael Jordan and Wilt Chamberlain were on the offensive end.

2. First Black Head Coach In The NBA

Russell was the first black head coach in any of the four main professional sports.

After legendary Celtics coach Red Auerbach decided to retire following the 1965–1966 season, Russell stepped into the role of head tactician. Russell spent the final three seasons of his Boston career as a player-coach. With him at the helm, the Celtics went 162-83 and won two NBA championships.

Russell also had coaching stints in Seattle and Sacramento. He didn't have much success in those two franchises, but his pioneering role still helped open coaching doors for blacks throughout the sports world.

1. 11 NBA Championships

For Russell, team success always took precedence over individual success. Winning 11 NBA championships in his career — including eight in a row — was a fruit of that mindset. No professional team in any of the four major sports has matched the Celtics' run of NBA championships from 1959 through 1966.

In those 11 championship teams, Russell was a bona fide leader. He may not have been the leading scorer, but he was the defensive anchor, the rebounding king, and the heart & soul. Russell was an All-Star in each of those seasons and the MVP in half of them.