Park Si Eun (박시은) is a South Korean singer and actress currently under High Up Entertainment. She is a member of the girl group STAYC and a former member of the trainee team i-Teen. Her father, Park Nam Jung, is a famous singer from the 80's. Sieun originally made her debut as a child actress in 2014 through the children's television series Pluto Secret Society.
On September 8, 2020 she was first member of STAYC to be revealed. She debuted on November 12, 2020 with the group's first single album "Star To A Young Culture".