Monstrum— Full Cast

Kim Myung-min

as Yun-gyeom

Kim In-kwon

as Seong-han / Mulgoe (voice)

Lee Hye-ri

as Myeong-i

Choi Woo-shik

as Royal Court Officer Heo

Lee Kyung-young

as Sim-un

Park Hee-soon

as King Jung-jong

Park Sung-woong

as Jin-yong

Lee Do-gyeong

as Grandpa Song

Lee Kyu-bok

as Mo-gae

Kim Joong-hee

as Mak-gae

Kim Kang-il

as First Vice-Premier

Cho Won-hee

as Second Vice-Premier

Jang Yong-bok

as Court Minister

Yun Hui-su

as Kang-nyeo

Han So-yeong

as Myeong-i's Mom