- Kim Yeong-cheol
- Â Baek San 36 episodes, 2009-2013
- Yun Ju-sang
- Â Oh Hyeon-Kyu / ... 32 episodes, 2009-2013
- Kim Seung-woo
- Â Park Cheol-yeong / ... 26 episodes, 2009-2013
- Lee Jung-Kil
- Â Jo Myeong-ho 25 episodes, 2009-2013
- Kim So-yeon
- Â Kim Seon-hwa / ... 21 episodes, 2009-2013
- Lee Byung-hun
- Â Kim Hyun-Jun / ... 21 episodes, 2009
- Kim Tae-hee
- Â Choi Seung-Hee / ... 21 episodes, 2009
- Jeong Jun-ho
- Â Jin Sa-Woo / ... 21 episodes, 2009
- Jang Hyuk
- Â Jung Yoo-Gun 20 episodes, 2013
- Lee Beom-su
- Â Yoo Joong-won 20 episodes, 2013
- Lee Da-hae
- Â Ji Soo-Yeon 20 episodes, 2013
- Im Soo-hyang
- Â Kim Yeon-hwa 20 episodes, 2013
- Yoon Doo-joon
- Â Seo Hyun-Woo 20 episodes, 2013
- Prince Oak Oakleyski
- Â Nightclub Owner 20 episodes, 2013
- Lee Na-kyung
- Â Young Jeong Soo-min 20 episodes, 2013
- Park Seo An
- Â Hyuk Soo 20 episodes, 2013
- Yun Je-mun
- Â Park Sang-hyeon 19 episodes, 2009
- Nah Yoon
- Â Hwang Tae-Sung 19 episodes, 2009
- Oh Yeon-su
- Â Deputy Director Choi Min 18 episodes, 2013
- David Lee McInnis
- Â Ray / ... 17 episodes, 2009-2013
- Kim Hye-jin
- Â Yang Jung-In 17 episodes, 2009
- Hyun Jyu-ni
- Â Yang Mi-Jeong / ... 17 episodes, 2009
- Soo-hyun Park
- Â Joong-Kwon / ... 17 episodes, 2009
- Baek Sung-hyun
- Â Kang Byung-jin 17 episodes, 2013
- Kim Il-woo
- Â Kang Cheol-Hwan / ... 17 episodes, 2013
- Hyun Jung Cha
- Â Yoo Hae Young 17 episodes, 2013
- Lee Joon
- Â Yoon Shi-hyuk 16 episodes, 2013
- Jeong Han-yong
- Â Jung Hyung-Joon / ... 16 episodes, 2009
- Myeong Ji-yeon
- Â Hong Soo-Jin 16 episodes, 2009
- Seung-hak Lee
- Â Kim Ji Hun 16 episodes, 2013
- Jeon Jae-hyeong
- Â Pyo Jin-hwan 15 episodes, 2013
- Choi Seung-hyun
- Â Vick 14 episodes, 2009
- Yong-gi Park
- Â Yoo Kang-Oh / ... 12 episodes, 2009
- Yoon So-yi
- Â Park Tae-Hee 12 episodes, 2013
- Hyeong-kon Kim
- Â Song Yeong-Min 11 episodes, 2013
- Jung-won Park
- Â Park Choon Sung 11 episodes, 2013
- Go Yoon-Hoo
- Â Yoo Jin 10 episodes, 2013
- Kim Ji-min
- Â Jamie 9 episodes, 2013
- Yûko Fueki
- Â Rie / ... 8 episodes, 2009-2013
- Choi Jong-hwan
- Â Yeon Gi-hoon 8 episodes, 2009
- Rich Ting
- Â Lee Cheol-Min 8 episodes, 2013
- Yoon Joo-hee
- Â Lee Soo-Jin 8 episodes, 2013
- Jo Sung-ha
- Â President Ha Seung-Jin 7 episodes, 2013
- Lee Bo-hee
- Â Jung Soo-Min / ... 7 episodes, 2013
- Jeong Seok-won
- Â Young Baek San / ... 6 episodes, 2013
- Kim Jong-goo
- Â Chief of Staff / ... 6 episodes, 2013
- Saejoon
- Â Lee Hyuk-Soo 6 episodes, 2013
- Kim Kap-su
- Â Yoo Jung-hoon / ... 5 episodes, 2009-2013
- Yeo Ho-min
- Â Hwang Soo 5 episodes, 2009
- Karen Miyama
- Â Yuki 4 episodes, 2009
- Joo Jin-mo
- Â Ha Jae-Yong 4 episodes, 2013
- Ki Yul Kim
- Â Oh Hyeon-Kyu's Nephew 4 episodes, 2013
- Ryu Seung-ryong
- Â IRIS soldier 3 episodes, 2009
- Eun-Chan Oh
- Â Kim Hyun-Jun (child) 3 episodes, 2009
- Kim So-hyun
- Â Young Ji Soo-Yeon 3 episodes, 2013
- Sung Dong-il
- Â Park Joon-han 3 episodes, 2013
- Gun-Tae Park
- Â Young Jung Yoo-Gun 3 episodes, 2013
- Na Yeon
- Â young Jung Soo-Min 3 episodes, 2013
- Narantsogt Tsogtsaikhan
- Â North Korean Agent 2 episodes, 2009-2013
- Tsogbaatar Batzorig
- Â North Korean Agent 2 episodes, 2009-2013
- Jeong Ho-bin
- Â Kang Cheol-Hwan 2 episodes, 2009
- Suk Goo Lee
- Â Yoon Sung Chul 2 episodes, 2009
- Park Sang-wook
- Â Chinese Firearms Dealer 2 episodes, 2013
- Kim Jeong-wook
- Â John 2 episodes, 2013
- Jo Han-chul
- Â Captain Jung 1 episode, 2009
- Kim Kyoo-tae
- Â Self 1 episode, 2009
- Yun-ho Yang
- Â Self 1 episode, 2009
- Tae-won Jeong
- Â Self 1 episode, 2009
- Jong-Ryul Choi
- Â Shin Yoo Sub 1 episode, 2009
- Masayuki Itô
- Â Japanese IRIS Soldier 1 episode, 2009
- Muh-sik Jeon
- Â Self 1 episode, 2009
- Takayama Satoichi
- Â Takashi Yamamoto 1 episode, 2009
- Jeon Jin-ki
- Â Phillip 1 episode, 2013
- Kang Shin-hyo
- Â Jang Chul 1 episode, 2013
