Yunjin Kim (born November 7, 1973) is a South Korea-born American  film and theater actress. She is best known for her role as Sun on the American television series Lost, and as a North Korean spy Bang-Hee in South Korean film Shiri.
She currently stars as Dr. Karen Kim in the ABC drama series Mistresses.
Kim was born in Seoul, South Korea on November 7, 1973. She emigrated to the United States with her family in 1980. They lived on Staten Island, New York. She joined the middle school drama club in the 7th grade and performed in the musical My Fair Lady.
After graduation, Kim devoted herself full-time to acting. She garnered several minor parts on MTV, in soap opera-style dramas on ABC, and on the off-Broadway stage. In 1997 she starred in Splendid Holiday, a Korean TV drama shot on location in New York. Kim decided to return to Korea. She was cast in the TV drama Wedding Dress and was also invited to act in Lee Kwangmo's feature Spring in My Hometown, although she ended up not taking this role. Her breakthrough debut came in the 1999 film Shiri, South Korea's first blockbuster film. Shiri became the highest grossing film in Korean history at the time. In November 2000 she continued her association with KangJeGyu in The Legend of Gingko.
After acting in a Japanese film and a feature set in Los Angeles, Kim appeared in the sci-fi feature Yesterday. Then in 2002, Kim took the lead role in Ardor, the feature film debut of documentarist Byun Young-ju. The film was invited to screen in a non-competitive section at the 2003 Berlin film festival.
In 2004, Kim started appearing in the U.S. television series Lost.
In May 2006, Maxim named Kim number 98 on its annual Hot 100 List. In October 2006 she was featured on the cover of Stuff, as well as an inside spread.
In 2013, she had a leading role in the ABC drama series Mistresses.