1. Cinderella's Sister (2010)
Kim Soo Hyun was cast for the role of Han Jung Woo, a character who has one-sided love for Song Eun Jo (Moon Geun Young). His casting fell through and the role went to Ok Taecyeon.
2. The Moon Embracing the Sun (2012)
Kim Soo Hyun and Moon Geun Young were both considered for the lead roles.
The synopsis and script went into her agency but never actually reached Moon Geun Young.
Joo Won was also originally cast for the role of Prince Yangmyung. In the end, Han Ga In got the lead role.
3. Film 'The Throne' (2015)
Kim Soo Hyun was offered the role of Prince Sado but he declined. Moon Geun Young was set to play the role Prince Sado's wife Lady Hyegyeong, and there were viewers eager to see the two of them finally meet however,Yoo Ah In and Moon Geun Young's casting were met with rave reviews.
-Woah ㅋㅋㅋㅋㅋㅋㅋ Please do a drama together before Kim Soo Hyun enlists
-I wish she had starred with Kim Soo Hyun in TMETS
-All the more reason for them to be paired up
-Would've been daebak if Moon Geun Young did TMETS, her acting is way better than Han Ga In