Dikembe Mutombo, a Basketball Hall of Famer who was one of the best defensive players in NBA history and a longtime global ambassador for the game, died Monday from brain cancer, the league announced. He was 58.

His family revealed two years ago that he was undergoing treatment in Atlanta for a brain tumor. The NBA said he died surrounded by his family.

“Dikembe Mutombo was simply larger than life,” NBA Commissioner Adam Silver said. “On the court, he was one of the greatest shot blockers and defensive players in the history of the NBA. Off the floor, he poured his heart and soul into helping others.”

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A Distinctive Presence on and off the Court

Mutombo was distinctive in so many ways — the playful finger wag at opponents after blocking their shots, his height, his deep and gravelly voice, his massive smile. Players of this generation were always drawn to him and Philadelphia 76ers star Joel Embiid, who was born in Cameroon, looked to Mutombo as an inspiration.

“It’s a sad day, especially for us Africans, and really the whole world,” Embiid said Monday. “Other than what he’s accomplished on the basketball court, I think he was even better off the court. He’s one of the guys that I look up to, as far as having an impact, not just on the court, but off the court. He’s done a lot of great things. He did a lot of great things for a lot of people. He was a role model of mine. It is a sad day.”

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An Illustrious NBA Career

Mutombo spent 18 seasons in the NBA, playing for Denver, Atlanta, Houston, Philadelphia, New York and the then-New Jersey Nets. The 7-foot-2 center out of Georgetown was an eight-time All-Star, three-time All-NBA selection and went into the Hall of Fame in 2015 after averaging 9.8 points and 10.3 rebounds per game for his career.

He also was part of one of the league’s most iconic playoff moments, helping eighth-seeded Denver oust top-seeded Seattle in the first round of the 1994 Western Conference playoffs. That best-of-five series marked the first time a No. 8 beat a No. 1 in NBA history.

“It’s really hard to believe,” Toronto President Masai Ujiri said Monday, pausing several times because he was overcome with emotion shortly after hearing the news of Mutombo’s death. “It’s hard for us to be without that guy. You have no idea what Dikembe Mutombo meant to me. … That guy, he made us who we are. That guy is a giant, an incredible person.”

A Legacy of Humanitarian Work

Mutombo last played during the 2008-09 season, devoting his time after retirement to charitable and humanitarian causes. He spoke nine languages and founded the Dikembe Mutombo Foundation in 1997, concentrating on improving health, education and quality of life for the people in the Congo.

Ryan Mutombo, the Hall of Famer’s son, said in a tribute posted on social media that his father “loved others with every ounce of his being.”

“My dad is my hero because he simply cared,” Ryan Mutombo wrote. “He remains the purest heart I have ever known.”

Mutombo served on the boards of many organizations, including Special Olympics International, the CDC Foundation and the National Board for the U.S. Fund for UNICEF.

“There was nobody more qualified than Dikembe to serve as the NBA’s first Global Ambassador,” Silver said. “He was a humanitarian at his core. He loved what the game of basketball could do to make a positive impact on communities, especially in his native Democratic Republic of the Congo and across the continent of Africa.”

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A Defensive Legend and Mentor

Mutombo is one of three players to win the NBA’s Defensive Player of the Year four times. The others: reigning DPOY winner Rudy Gobert of the Minnesota Timberwolves, and Hall of Famer Ben Wallace.

“He was always there to talk to me and advise me on how to approach the season and take care of my body and icing after games and stretching and trying different things like yoga,” Milwaukee Bucks star Giannis Antetokounmpo said. “He will be always remembered and may his soul rest in peace.”

Philadelphia 76ers president Daryl Morey — who was with Mutombo for many seasons in Houston — was informed of his friend’s death during the team’s media day on Monday. Tears welled in Morey’s eyes as he processed the news.

“There aren’t many guys like him,” Morey said. “Just a great human being. When I was a rookie GM in this league, my first chance in Houston, he was someone I went to all the time. … His accomplishments on the court, we don’t need to talk about too much. Just an amazing human being, what he did off the court for Africa. Rest in peace, Dikembe.”