The jailing of a South Korean religious leader on Thursday for the rape of multiple followers is only the latest example of such abuse.
The world's 11th-largest economy is technologically advanced but has a history of cult organisations and charismatic religious leaders, some of whom have amassed enormous wealth and influence.
Here are some groups that have previously attracted controversy or had brushes with the law.
- World Mission Society -
The World Mission Society Church of God predicted the end of the world would come on December 31, 1999.
The continued existence of the earthly realm has been no barrier to its fortunes, and an anti-cult group estimates that it has more than 200,000 followers, although it claims more than two million.
Its founder Ahn Sang-hong, who died in 1985, is in effect worshipped as the Heavenly Father, who it says will come for the salvation of 144,000 souls -- the number appears in a biblical prophecy.
Ahn's wife Jang Gil-ja is regarded as the Heavenly Mother. Its aggressive evangelical activities in Southeast Asian countries sparked controversy.
- Temple of the Tabernacle -
Shincheonji, or the Temple of the Tabernacle of the Testimony, suggests that its founder Lee Man-hee has donned the mantle of Jesus Christ and will take 144,000 people with him to Heaven, body and soul, on the Day of Judgement.
But its adherents have long surpassed that number, and critics say they have to engage in endless loyalty competitions to earn credits to be included among the saved, sacrificing their everyday lives and leading to serious family disputes.
Shincheonji "is the nation of God, created by Him to fulfil what is in heaven on this earth in today’s time", it says on its homepage, adding that Lee "is creating God’s kingdom of heaven here on earth, exactly as he witnessed it in heaven".
- Grace Road Church -
The female leader of a doomsday cult and three of her acolytes were arrested this year for allegedly holding some 400 followers captive in Fiji and subjecting them to violence and barbaric rituals.
Victims were hit hundreds of times in ceremonies known as "threshing floors", defectors told South Korean media.
Shin Ok-ju, founder of the Grace Road Church, has gone on trial on charges of violence, child abuse, exploitation and incarceration, among others.
- Providence -
One of South the largest and best-known cults is Providence or Jesus Morning Star, also known by the acronym JMS -- which matches the initials of its founder Jung Myung Seok.
He set it up in 1980 as a breakaway from the Unification Church, also known as the Moonies.
Jung was released from prison earlier this year after serving a 10-year sentence for the rape and sexual assault of four female followers.
He told them to have sex with him to purge themselves of sin.
- Salvation Sect -
Guwonpa, or "Salvation Sect", came to national attention when the Sewol ferry -- whose operating company was run by its leader Yoo Byung-eun and his family -- sank in 2014 with the loss of more than 300 lives, most of them children.
On the run from charges of corruption and negligence, Yoo's body was found in a field, so badly decomposed that authorities were unable to determine the precise cause of death.
- Five Oceans -
In 1987, 32 members of an apocalyptic cult called Odaeyang, meaning "five oceans", were found dead at their headquarters in the southern city of Yongin in an apparent murder-suicide pact.
Among them was the cult's leader Park Soon-Ja, who had been under pressure from her lenders over $17 million of debts and was under police investigation for embezzlement.
Police said Park's two sons and a cult official strangled her and 28 others before killing themselves.