Park Bo Gum as Lee Yeong (later Crown Prince Hyomyeong)
– Jung Yoon Suk as Lee Young (child)
Kim Yoo Jung as Hong Ra On
– Kim Ji Young as Ra On (child)
Jin Young as Kim Yoon Sung
– Lee Hyo Je as Yoon Sung (child)
Chae Soo Bin as Jo Ha Yeon (later Crown Princess Jo)
Kwak Dong Yun as Kim Byung Yun
– Noh Kang Min as Byung Yun (child)

Palace

Kim Seung Soo as King Sunjo
Jun Mi Sun as Royal Consort Suk Ui
Jung Hye Sung as Princess Myung Eun
Heo Jung Eun as Princess Young Eun
Jung Yoo Min as Wol Hee

Kim Clan

Chun Ho Jin as Kim Hun (Yoon Sung’s grandfather)
Han Soo Yun as Queen Kim (Kim Hun’s daughter)
Park Chul Min as Kim Eui Gyo
Bang Joong Hyun as Kim Geun Gyo

Jo Clan

Lee Dae Yeon as Jo Man Hyung (Ha Yun’s father)

Eunuchs

Jang Kwang as Han Sang Ik
Lee Joon Hyuk as Eunuch Jang
Tae Hang Ho as Do Gi
Oh Ui Shik as Sung Yeol
Jo Hee Bong as Eunuch Sung
Choi Dae Chul as Ma Jong Ja

Others

Ahn Nae Sang as Jung Yak Yong
Kang Ki Doong as Dal Bong
?? as Jang Gi Baek
Ahn Se Ha as Jung Duk Ho
Jung Hae Kyun
Kim Jong Goo
Kim Ki Chun
Kim Byung Chul
Cha Joo Young
Lee Jung Sung
Choi Na Moo