The actor who starred as a wealthy and shallow patriarch in Bong Joon-ho's Oscar winning movie in 2019, was found dead in a vehicle, which was parked on the street in Seoul's mid-northern Seongbuk.
An official from the Seongbuk police station confirmed this news in a statement. "We believe his body has now been transferred to the Seoul National University Hospital," he added.
A news agency in South Korean, Yonhap, reported that Lee had also left a "note that reads a will".
Along with his role in Parasite, Lee was also celebrated for a variety of roles, including his portrayal of a diligent architecture, facing personal problems in 2018 TV drama, My Mister, as well as being recognised for performances in TV drama Coffee Prince (2007), and the film All About My Wife (2012).
Lee's last film Sleep, a horror where he played a husband whose sleepwalking leads him to disastrous consequences, also featured in the Critics Week section at the Cannes Festival. That film was released this year.
However, having been known for his squeaky-clean image, Lee became the subject of a police investigation in October, over his alleged use of marijuana and other drugs, which erupted into a major scandal, and led to him being dropped from several television and commercial projects, according to various media outlets.
This happened after Lee had been accused of taking drugs at the residence of a hostess from a high-end bar in Seoul's Gangnam district. Although, Lee had claimed that the hostess had "tricked" him into taking these drugs, and was unaware that they were illegal.
Lee had attended a third police investigation which ended on Christmas eve, having lasted for 19 hours.
"I sincerely apologise for causing great disappointment to many people by being involved in such an unpleasant incident," Lee told reporters. "I feel sorry for my family, which is enduring such difficult pain at this moment".
"Once again, I sincerely apologise to everyone".
South Korea have strict rules on drug use, with Koreans found to have taken substances such as marijuana legally abroad facing possible prosecution when they return to their home country.
Following confirmation of the actor's death, fans have been leaving heartfelt messages on social media, in tribute to Lee Sun-kyun.
"I laughed and cried a lot while watching your acting. Thank you", one fan wrote.
Korean-American writer Min Jin Lee also paid homage to the late actor.
"Lee was praiseworthy in Parasite and exceptional in My Mister," she added. "May he be remembered for his excellent work and creative gifts".
Lee is survived by his wife, actress Jeon Hye-jin and two sons.
