Michael Alig — one of the ringleaders of the Club Kids — died from an overdose of several hard drugs has learned.

The Office of Chief Medical Examiner in NYC tells us … Alig’s cause of death was acute intoxication by fentanyl, acetylfentanyl, heroin and methamphetamine.

We broke the story … Alig — the notorious club promoter who was the subject of the 2003 Macaulay Culkin movie “Party Monster” and the 2015 documentary ‘Glory Daze’ — was found dead in his NYC home on Christmas.

Law enforcement sources tell us … a friend discovered Alig unconscious and unresponsive on his bed and called 911. He was pronounced dead on the scene.

We’re told cops found 2 to 3 small bags of heroin and other empty bags near his body … prompting their suspicion he’d died from an OD. The Medical Examiner says it was an accidental overdose.

54-year-old Alig, known as the “king of the Club Kids,” pled guilty to first-degree manslaughter in 1997 in the killing of fellow Club Kid, Andre “Angel” Melendez. He served 17 years before his release in 2014.