Jo Min-ki had been accused of sexual assault of at least eight people amid a string of #MeToo allegations in the country.
The actor was found dead at his home in Seoul, reported a news agency Yonhap and the Korea Times, who cited police.
Min-Ki’s roles were primarily in TV shows, but he also appeared in a number of films. He was due to be questioned by police next week, the reports said.
The 52-year-old was one of the biggest names to be ensnared in South Korea’s #MeToo movement.
He was accused of sexually harassing and raping students at Cheongju University, where he had taught for the past few years.
Jo was dismissed from his post last month as a result of the allegations.
He initially denied any wrongdoing but released a statement on 27 February apologizing to his accusers.
“Everything is my fault, and I am the one to be blamed,” he said. “I am deeply sorry to all the victims for the pain I’ve caused, and from here on out, I will not avoid the social and legal consequences of my mistakes.”
The actor was also edited out of TV drama Children of the Small God and replaced by Lee Jae Yong.