Kim Byeong-ok

Shin Hong-geun

Yang Sun-dong: the nationwide leader of Oh Kyung-sook's party.

Kang Dae-wook

Bang Dae-han, the CEO of B&G Law Firm.

Chairman Lee Go Se-won as young Chairman Lee (Ep. 11–12)

Lee Byung-hak

Yoon Choon-sang

Choi Gi-il, Ban-do's father

Yoon Jong-soo, Ji-ho's father who is a car center operator.

Detective agency manager Han

Park Sun-jae

Magistrate Uhm Ja-chi

Plastic surgeon (cameo)

Jung Jung-ki – 54-year-old, Kangnam Police station's homicide investigation team leader

Yeom Tae-cheol

Hyun-joon's older brother

Jo Chul-wang, Jo Seok's father, who works a chicken shop that barely gets customers (due in part to closing early half the time)

Hired killer

Choi Ji-mong

Shim Bong-seo, loan shark

Fortune teller

Go Bok-tae

Go-bong's doctor

Jeoul ("Scale"), head of the narcotics ring (drugs, loan sharking, adult entertainment establishments), and leader behind the scenes of "Halibut" and "Meth Kim".

Hwang Jong-pal

Hwang Dal-joong, Joon-gook's cellmate

Nursing home director (ep 11)

Director Kim