Kyung-chul is a dangerous psychopath who kills for pleasure. Soo-hyeon, a top-secret agent, decides to track down the murderer himself. He promises himself that he will do everything in his power to take vengeance against the killer, even if it means that he must become a monster himself.
You can now watch I Saw the Devil online on the following streaming providers in the United States.
| Writing | Park Hoon-jung | Screenplay |
| Sound | Mowg | Original Music Composer |
| Lighting | Oh Seung-chul | Gaffer |
| Camera | Lee Mo-gae | Director of Photography |
| Editing | Nam Na-young | Editor |
| Directing | Kim Jee-woon | Director |
| Writing | Kim Jee-woon | Screenplay |
| Art | Jo Hwa-seong | Production Design |
| Costume & Make-Up | Kwak Tae-yong | Makeup Effects Designer |
| Costume & Make-Up | Lee Hee-eun | Makeup Effects Designer |
| Sound | Romain Bigorgne | Sound Effects Editor |
| Sound | Choi Tae-young | Supervising Sound Editor |
| Sound | Choi Tae-young | Sound Re-Recording Mixer |
| Sound | Dong-Han Kim | Sound Effects Editor |
| Sound | Park Yong-gi | Sound Re-Recording Mixer |
| Crew | Jung Doo-hong | Fight Choreographer |
| Camera | Kim Byung-seo | Camera Operator |
| Sound | Gang Hye-yeong | Sound Editor |
| Art | Son Min-jeong | Conceptual Design |
| Costume & Make-Up | Kim Hyun-jung | Makeup & Hair |
| Directing | Seok Min-u | Assistant Director |
| Costume & Make-Up | Kwon Yoo-jin | Costume Design |
| Editing | Kim Mi-young | Editor |
| Art | Kim Byung-han | Conceptual Design |
| Production | Kim Jae-young | Producer |
| Production | Kim Jung-hwa | Producer |
| Production | Cho Seong-won | Co-Executive Producer |
| Production | Kim Hyun-woo | Executive Producer |
| Production | Nam Seong-ho | Line Producer |
| Art | Kim Cho-hea | Set Decoration |
| Crew | Heo Myeong-haeng | Fight Choreographer |
| Visual Effects | Jung Sung-jin | Visual Effects Supervisor |
| Costume & Make-Up | Pi Dae-seong | Special Effects Makeup Artist |
| Crew | Lee Hee Kyung | Special Effects |
| Visual Effects | Kang Jong-ik | VFX Supervisor |
| Visual Effects | Jung Do-ahn | Special Effects Supervisor |
| Art | Jeon Sung-ho | Set Decoration |
| Crew | Han Jeong-uk | Stunts |
| Sound | Kim Kyung-tae | Production Sound Mixer |
| Writing | Lee Yoon-ho | Storyboard |
| Editing | Kim Hyung-seok | Digital Colorist |
| Camera | Lee Jong-woo | Camera Operator |
| Visual Effects | Yang Il-seok | VFX Supervisor |
| Visual Effects | Son Seung-hyeon | VFX Supervisor |
| Camera | Lee Jae-hyeok | Still Photographer |
