Oh Man-seok

as Jang Suk-ho (7 episodes)

as Kim Jung-hoon (1 episode)

as Zookeeper (segment "Chimpanzee")

as Hong Jeong-pyo (12 episodes)

as Lee Dong-joon (12 episodes)

as Professor Sin

as Bong-sam

as Tae-geun

as Lee Je-hee Foundation Secretary

as Lee Taek-yeol (16 episodes)

as Um Sun-gu (12 episodes)

as Woodsman (2 episodes)

as Kwon Ji-woong (14 episodes)

as Choi Dong Joon [Ro Hee's great-uncle] (12 episodes)

as Yoo Gyo-yeon (21 episodes)

as Ji-eun's father (8 episodes)

as No Yu Cheol (12 episodes)

as Reporter Kang

as Designer Lee [Hyun Joo's father] (1 episode)

as Choi Young-hwan

as Lee Young Goon [Professor] (4 episodes)

as Yun Taek Il [Seung Beom and Sun Ho's dad] (5 episodes)

as Kang Joo-man (16 episodes)

as Park Hyeong Su [Jing Seong's father] (12 episodes)