A Werewolf Boy

Song Joong-ki

Wolf-Boy / Chul-soo

Park Bo-young

Young Sun-yi / Eun-ju

Yoo Yeon-seok

Ji-tae

Lee Young-ran

Sun-yi

Jang Young-nam

Sun-yi's Mother

Kim Hyang-gi

Sun-ja

Yoo Seung-mok

Professor Kang Tae-shik

Shin Bi

Dong-mi

Woo Jung-kook

Mr. Jung

Goo Bon-im

Mrs. Jung

Lee Jun-hyeok

Policeman

Soel Oh-shin

Thug 1 (uncredited)