Lee Sun-Kyun, a South Korean actor of the Oscar-winning film "Parasite", was found dead, Yonhap news agency reported on Wednesday.
Lee had been under investigation over illegal drug use allegations amid an ongoing government crackdown on illegal drugs.
Lee was found unconscious next to briquettes inside a car at a park in Seoul on Wednesday morning, after his wife reported to police that Lee had left home and she had found what appeared to be a suicide note, Yonhap said, citing police.
South Korea has tough drug laws, and drug crimes are typically punishable by at least six months in prison or up to 14 years for repeat offenders and dealers.
Born in 1975, Lee starred as a rich family's father in "Parasite", and also played leading roles in South Korean movies including the 2012 thriller "Helpless" and 2014's "All About My Wife", among others.
Lee had the lead role in Apple TV+'s first Korean-language original series, which rolled out in 2021. "Dr. Brain", a six-episode sci-fi thriller, was about a cold-hearted neurologist, Koh Se-won, who tries to find clues to a mysterious family accident through brain experiments.