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 after a battle with 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."

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, four-time defensive player of the year, 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.

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.

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."