What's Up Fox is a 2006 South Korean television series, starring Go Hyun-jung and Chun Jung-myung. It aired on MBC from September 20 to November 9, 2006 on Wednesdays and Thursdays at 21:55 for 16 episodes. The romantic comedy explores age differences in relationships, in particular between a 33-year-old woman and her best friend's brother who is nine years younger.

Go Hyun-jung, or Ko Hyun-jung, is a South Korean actress and beauty pageant titleholder. She debuted in the entertainment industry as a Miss Korea runner-up in 1989 and went on to star in Sandglass (1995), one of the highest-rated and critically acclaimed dramas in Korean television history. She retired after marrying chaebol Chung Yong-jin in 1995, then returned to acting after their divorce in 2003. Go has since regained her top star status in Korea, becoming the highest-paid actress on TV after the success of her series Queen Seondeok (2009) and Daemul (2010).