HQ Trivia founder Colin Kroll died from a lethal cocktail of drugs including fentanyl, officials revealed Tuesday.

Kroll’s accidental Dec. 16 death was caused by the “combined effects of fentanyl, fluoroisobutyryl fentanyl, heroin, and cocaine,” the chief medical examiner announced.

Police discovered the 34-year-old tech whiz — who also co-founded Vine — lying face-down in the bedroom of his Nolita apartment on Spring Street, after his girlfriend called 911 saying she had been unable to get in touch with him.

Law enforcement sources at the time said marijuana and heroin were found near his body, along with an envelope containing a white powdery substance.

He was pronounced dead at the scene.

Kroll’s ex-fiancee, Maggie Neuwald, previously told The Post he was “overwhelmed with success.”

“It’s not like anyone hands you … a manual of how to deal with [whirlwind success],” Neuwald said. “That probably, unfortunately, got the best of him, although I had hoped he’d be able to fight those demons.”