Chae Yeon’s real name is Lee Jung Sook
Jang Hyuk’s real name is Jung Yong Joon
Ryu Jin’s real name is Kim Yoo Jin
Won Bin’s real name is Kim Do Jin
Gong Yoo’s original name is Gong Ji-cheol
Hyun Bin’s original name is Kim Tae-pyeong
Hyun-young’s original name is Yoo Hyun-young
Lee Wan’s original name is Kim Hyung-soo
Jicheng’s original name is Kwak Tae-geun
Bin Yu’s original name is Kim Ji Young
Shen Ae’s original name is Zhao Xin Ai
Ryu Sun’s original name is Wang Youshan
Shin Ji’s original name is Li Jishan
I am thinking of Jiang Zhe, but I don’t know if it is his original name, it seems not.
Also Jin Min
Gao Xiu may be his original name