Nak-won

Baek Jang -ho (1 episode)

Bang Ki-ho (12 episodes)

Cha Gi-baek (12 episodes)

Choi Han-gyu

Hwang Dong-woo (16 episodes)

Oh Yeong-geun (12 episodes)

Jung-su

Park Jin-suk (16 episodes)

Kim In-su (1 episode)

President Han (16 episodes)

Teacher Baek (32 episodes)

Chae Byung-Hak (16 episodes)

(1 episode)

Noh Joon-suk (2 episodes)

Kim Je-seok

Lee Young-Joon (40 episodes)

Lee Sun-Moon (16 episodes)

Jang Tae-joon (20 episodes)

Cha Jae-hwan (20 episodes)

Byun Dae-sung (20 episodes)

Han Pan-seok (102 episodes)

Kim Geon-pyo (37 episodes)

Chairman Kim Nam-yoon (20 episodes)

(93 episodes)

Seo Dae-Seok (18 episodes)

Kim Yongchun (70 episodes)

Kim Seok-joon (20 episodes)

Chae Dae-pil (5 episodes)

Lee Hoe-young (6 episodes)

Oh Tae-suk (60 episodes)

(24 episodes)

Jang Kil-Taek (16 episodes)

Park Jae-hyun (23 episodes)

Kang Sang-maan

Chang-sik (20 episodes)

Kang Dong-hyun (20 episodes)

(4 episodes)

(165 episodes)

Park Jin-kwon (16 episodes)

Yoon Myung-hoon (20 episodes)

Yoon Soo-ha (2006) (10 episodes)

(8 episodes)

Ji Kyung-hwan (18 episodes)

Department Head Nam

Kim Soo-bong (16 episodes)

Kim Jae-man (52 episodes)

Manager Jin (12 episodes)

(124 episodes)

Professor Kim Jin-woo (20 episodes)

(16 episodes)

Professor Yoon (16 episodes)

(1 episode)

Jong-goo (2 episodes)

(1 episode)

Kim Seok Ju (63 episodes)

Jung-yong

(1 episode)