Kim Yoo-Jung is a South Korean actress. She debuted as a model for a confectionery brand at the age of four. After her acting debut in 2003, she became one of the most in-demand child actresses in Korea. She gained public attention for starring in the television series Dong Yi (2010), Moon Embracing the Sun (2012), May Queen (2012), Golden Rainbow (2013), Secret Door (2014), and Angry Mom (2015). She also starred in the films Commitment (2013), Thread of Lies (2014), and Circle of Atonement (2015). She hosted the music show Inkigayo from November 2014 to April 2016.

She took on her first leading role in the historical romance drama Love in the Moonlight (2016) and starred in the romantic comedy film Because I Love You (2017), television drama Clean with Passion for Now (2018), Backstreet Rookie (2020), mystery thriller film The 8th Night (2021), historical fantasy romance drama Lovers of the Red Sky (2021), and teen romance film 20th Century Girl (2022).

Kim has been nicknamed "Nation's Little Sister" after playing various child roles and "Sageuk fairy" after taking roles in several acclaimed historical dramas in her career. She also gained the nicknames "Nation's First Love" and "Global First Love" following her well-loved performance in 20th Century Girl. In 2017, she ranked 8th on the Forbes Korea Power Celebrity list, the youngest to be included in the Top 10 at the age of 17.