Kim Si-hyeon (; born August 5, 1999), known mononymously as Sihyeon, is a South Korean singer and actress. She is the leader and vocalist of girl group Everglow, formed by Yuehua Entertainment.
Kim was born on August 5, 1999, in Bundang District, Seongnam, South Korea. In 2016, Kim competed in the first season of Mnet's reality television competition Produce 101 where she got finished at the 40th placed afterwards, and signed a contract with Yuehua Entertainment. In 2018, Kim joined the third season of the franchise, Produce 48 alongside future group mate Wang Yiren. Kim placed 27th and was once again eliminated in the third round with Wang Yiren.
Kim debuted with Everglow on March 18, 2019. Everglow released their first single album, Arrival of Everglow, with the lead single "Bon Bon Chocolat", with their debut showcase. On February 7, 2020, Kim was chosen as a new MC for SBS MTV's music program "The Show" alongside The Boyz's Juyeon and Kim Min-kyu. On May 25, 2021, it was announced that Kim would be replacing E:U as the leader of Everglow, as E:U stated that she didn't have any strength while being a leader. On April 12, 2024, it was announced that Kim would be making her acting debut in the television series Salon de Holmes.