Kim You-jung (Korean: 김유정; born September 22, 1999) is a South Korean actress. She started out as a model for a confectionery brand at the age of four and after her acting debut in 2003, Kim became one of the most in-demand child actresses in South Korea leading her to be called "Nation's Little Sister". Through her roles in several acclaimed historical television series in her teens, she has also been referred to as "Sageuk Fairy" by media outlets.[2][3] Kim had her first starring role in the historical romance Love in the Moonlight in 2016 which catapulted her to fame as a leading actress in television and film. In 2017, she ranked 8th on Forbes Korea Power Celebrity list, the youngest to be included in the Top 10 at the age of 17.[4] With roles across genres, she further received attention for her performances in the romantic-comedy Backstreet Rookie (2020), historical fantasy Lovers of the Red Sky (2021), teen romance film 20th Century Girl (2022), fantasy romance My Demon (2023–2024), and psychological thriller Dear X (2025).[5] She gained the nicknames "Nation's First Love" and "Global First Love" following her performance in 20th Century Girl.[6][7]