K-pop star Sulli, formerly a member of the band f(x), has died aged 25.
Police told the BBC the singer's manager found her dead at her home near Seoul, South Korea.
The cause of her death is still being investigated, but fans and fellow K-pop stars have been paying tribute to the star online.
Sulli, who had more than five million followers on Instagram, was a member of f(x) until she left in 2015 to focus on her acting career.
Some believe the artist, whose real name is Choi Jin-ri, suspended her K-pop work after struggling with the abuse she got online.
Police have said they believe Sulli may have taken her own life but are investigating all possibilities.
'She clapped back'
Music journalist Taylor Glasby said Sulli was a "free spirit".
"She was one of the idols who decided to live her life in the way she wanted to and that didn't always sit well with the general public," she tells Radio 1 Newsbeat.
In South Korea, pop stars are called idols.
"For idols, everything is about appearance, everything is quite monitored and she just didn't [monitor her content]. She was herself".
"She clapped back and she wouldn't take people's narrow-mindedness".
Taylor says Sulli's former band f(x) changed K-pop.
"They were one of the girl groups that didn't fit in, they did their own thing. Their music was more hard-hitting. It was innovative and complex, and it helped cement an entire sub-genre within K-pop - girl crush.
"When she left, her legacy became being outspoken. It became taking control of her own image. I admired her spirit to do so despite the constant negativity that was directed at her by some less open minded citizens."
Sulli's former f(x) bandmate, Amber Liu, has posted her shock at what's happened.
Due to recent events i’ll be putting on hold my upcoming activities. Sorry everyone.— Amber J. Liu 刘逸云 (@llama_ajol) October 14, 2019
Thank you for your thoughts.
Sulli was known for being outspoken and breaking the K-pop mould. She unashamedly told her fans that they had a choice about how to display their bodies.
She was involved in the so-called "no bra" movement in South Korea - where women go braless to make a statement about expectations and judgement of their bodies.
Sulli showed her nipples on social media on a number of occasions - the first appeared on her Instagram account in May 2016. She faced a huge amount of abuse in response.
Last month her breasts were shown by accident during a live Instagram stream - which again caused controversy in conservative South Korea.
Sulli was good friends with K-pop star Jonghyun, who took his own life aged 27.
The artist paid tribute at his funeral in 2017.
중앙자살예방센터 (Korea Suicide Prevention Center)https://t.co/ScEX6xj469— Laura Bicker (@BBCLBicker) October 14, 2019
보건복지부 보건복지콜센터 (Ministry of Health & Welfare Call Center)
129 (24시간 위기상담 / 24 hour hotline)
If you or someone you know are feeling emotionally distressed, these organisations offer advice and support. In addition, you can call the Samaritans free on 116 123 (UK and Ireland). Mind also has a confidential telephone helpline- 0300 123 339 (Monday-Friday, 9am-6pm).