Jo Sung-ha

Lee Chang-woo

King Seongjo

Lee Moo-young, Chae-rok's father who used to be a soccer coach at his school before going to jail. He was released recently and lives apart from his son to make a living.

Jo Ki-soo

Lee Shin-woong, head of the entire police department. He is responsible for covering up the murder and rape that happened 20 years ago. He is arrested in the end for corruption.

King (Ep. 1–2)

Kim Cha-eon

The man reading a newspaper who told Ma-wang the time in the movie (Ep. 5)

Baek Jung-ki

Song Jae-joon

Im Tae-Ho – A married police officer with 3 kids, Tae-Ho manages a subcontracting company in secrecy to support his family. He hires Chan-gyu as one of his employees to keep tabs on officials and persons.

Jang Se-joon

Kang Joo-sun, Kang In-woo's father

Go Min-joong

Dam Pyeong-joon

Ha Seung-jin

Park Do-myung, chief presidential secretary

Dr. Seok Min-hyuk (cameo, ep 1, 12, 20)

Hwang Yong

Jin-young's father

Park Dong-jae's father (cameo)

Kim Young-joon

Lee Jae-joon

King Jeongjo of Joseon

Yi Su

Eom-soo