Ash has seen this movie.
A teenage girl is captured by a giant mutated squid-like creature that appears from Seoul's Han River after toxic waste was dumped in it, prompting her family into a frantic search for her.
| Park Gang-du | Song Kang-ho |
| Park Hie-bong | Byun Hee-bong |
| Park Nam-il | Park Hae-il |
| Park Nam-joo | Bae Doona |
| Park Hyun-seo | Ko A-sung |
| The Monster (voice) | Oh Dal-su |
| Se-jin | Lee Jae-eung |
| Se-joo | Lee Dong-ho |
| Homeless Man | Yoon Je-moon |
| Fat Guevara | Yim Pil-sung |
| Yellow Suit at Funeral | Kim Roi-ha |
| Hostage nurse | Koh Soo-hee |
| Civilian Military Kim | Kim Hak-seon |
| Douglas | Scott Wilson |
| Young Korean Doctor | Brian Rhee |
| American Doctor | Paul Lazar |
| Donald | David Anselmo |
| Fumigation Truck Skinny Man | Baek Do-bin |
| U.S. Senator (uncredited) | Martin Lord Cayce |
| Man from Duck Boat (uncredited) | Choi Dae-sung |
| Man on Blind Date (uncredited) | Choi Doo-yeong |
| Detective Agency Subordinate 1 (uncredited) | Choi Jae-sup |
| Woman with Long Hair (uncredited) | Jung Seo-yoon |
| Additional Voices (voice) (uncredited) | Philip Hersh |
| Isolation Ward Doctor (uncredited) | Jeong In-gi |
| 4th Mat 3 (uncredited) | Jeong Hyeong-Ho |
| Camera Phone Man (uncredited) | Ji Ha-geon |
| Camera Phone Woman (uncredited) | Moon Hee-Ra |
| Mr. Yoon's Employee (uncredited) | Jeong Kang-hee |
| Isolation Ward Nurse 1 (uncredited) | Kim Bi-bi |
| Woman crying (uncredited) | Kim Choo-wol |
| 5th Mat Woman (uncredited) | Kim Da-yeon |
| Quarantine Hospital Nurse 2 (uncredited) | Kim Hyo-sun |
| Woman from Couple (uncredited) | Kim Jin-seon |
| Woman from Duck Boat (uncredited) | Kim Nan-hee |
| Old Security Guard (uncredited) | Kim Sang-jo |
| Bride-to-be (uncredited) | Kwon Bang-hyeon |
| Doctor from Isolation Ward 1 (uncredited) | Kwon Byung-gil |
| Fisherman 1 (uncredited) | Kwon Hyeok-pung |
| 4th Mat 2 (uncredited) | Lee Dong-yong |
| Man from Couple (uncredited) | Lee Eung-jae |
| Fat Man (uncredited) | Lee Hoon-jin |
| 4th Mat 1 (uncredited) | Lee Jong-yoon |
| Girl's Father (uncredited) | Lee Seung-jin |
| Altar Security (uncredited) | Min Kyung-jin |
| Agent Yellow (uncredited) | Clinton Morgan |
| Fumigation Truck Dyed-hir Man (uncredited) | Park Jeong-gi |
| Groom-to-be (uncredited) | Park Kyeong-mok |
| Inquiry Officer | Park No-shik |
| Woman Stomping Her Feet (uncredited) | Ra Mi-ran |
| Exchanged Girl (uncredited) | Seo Ha-neul |
| Donald's Girlfriend (uncredited) | Shin Seung-ri |
| Mr. Yoon's Friend (uncredited) | Shin Hyeon-jong |
| Grandmother from Bus (uncredited) | Son Young-soon |
| Doctor from Isolation Ward 2 | Son Jin-ho |
| Woman on Blind Date (uncredited) | Song Kyeong-ha |
| Taxi Driver | Yoo Seung-mok |
| District officer Mr. Jo (uncredited) | Yoo Yeon-soo |
| Protester | Seo Young-ju |
| Nurse | Ko Chang-seok |
| Isolation Ward Constable (uncredited) | Park Jin-woo |
| Park Ji-hwan | |
| Nursing assistant | Yoo In-soo |
