Mutt Boy (; lit. "Shit dog") is a 2003 South Korean film starring Jung Woo-sung, Kim Kap-soo and Uhm Ji-won. A developmentally-disabled boy grows up in a rural town, and eventually attracts a small gang of followers due to his fighting skills. However, he keeps getting into trouble against the law, and getting picked up by his father who works as a police officer.

Plot

Chul-min's family consists of himself, his police detective father, his sick mother, and a dog. Chul-min calls the dog "Mutt" or "Stray Dog," but his father calls Chul-min "Mutt" too. The dog is Chul-min's best friend. He doesn't cry when his mom dies, but he does get furious when his dog is eaten by the older boys in his soccer club. He takes his revenge, but his father's patrol car awaits him. Although he now must live on his own, Chul-min wins renown as the one who beat up 21 people all by himself. Many of the town's thugs start to hang around Chul-min, fascinated by him, and he becomes a leader of small-time gangsters. One day his father takes in a young orphan named Jung-ae who was a thief. Eventually Chul-min and Jung-ae develop feelings for each other and Chul-min confronts the gang who killed his beloved dog.