Koo Hye-sun is a South Korean actress, singer-songwriter, director and artist. She gained widespread recognition in the television dramas Hearts of Nineteen (2006), The King And I (2007), Boys Over Flowers (2009), Take Care of Us, Captain (2012), Angel Eyes (2014), Blood (2015).

Hearts of Nineteen is a 167-episode South Korean television drama/romantic comedy broadcast by KBS1 from mid 2006 to early 2007. The drama won many awards at 2006 KBS Drama Awards and was a commercial success reaching a peak rating of 43.2% on its January 6 episode and an average viewership of 29.14%.