Chuck Negron — one of the founding members and frontman of rock band Three Dog Night — has died.

The singer died on Monday at his home in Studio City, CA surrounded by family, according to his obituary. A cause of death has not been immediately revealed, but the singer battled chronic obstructive pulmonary disease (COPD), for decades, and suffered from heart failure at the end of his life.

Negron was born in 1942 and raised in the Bronx, New York, and moved to Los Angeles to play basketball for California State University. During this time, he explored music as he had grown up singing in doo wop groups.

He formed Three Dog Night in 1967 with Danny Hutton and the late Cory Wells, and their genre-defying blend of R&B, rock ‘n’ roll and urban doo-wop music paired with modern, forward-looking production helped them become one of the biggest groups of the ‘60s and early ‘70s.

Some of their biggest songs include “Joy To The World (Jeremiah Was A Bullfrog),” “One (Is The Loneliest Number),” “Easy To Be Hard,” “Black and White” and “Mama Told Me (Not to Come).” The band’s final Billboard Hot 100 hit came with 1975’s “Til the World Ends.” The band broke up in 1976 due to internal conflicts.

Negron struggled with his skyrocketed fame and fell into deep drug use — he even spent his entire earnings on drugs and hit rock bottom when he called Skid Row his home. After cycling through rehab several times, he got clean in 1991 and pulled off a major comeback, launching a successful solo career that saw him release 7 albums between 1995 and 2017.

He recalled his ups and downs with addiction in his acclaimed 1999 book, “Three Dog Nightmare.”

He is survived by his wife Ami Albea Negron, his children Shaunti Negron Levick, Berry Oakley, Charles Negron III, Charlotte Negron, and Annabelle Negron, his brother Rene (Jody) Negron, sister Denise (Janey) Negron and his 9 grandchildren, 5 nieces and 2 nephews.

He was 83.