Billy" Chapman is the main antagonist villain of Silent Night, Deadly Night.
He was portrayed by Robert Brian Wilson.
Billy, his brother Ricky, and their parents, were heading home after visiting his grandfather. Billy's parents were killed by a thief dressed as Santa Clause. Billy survived by running off and hiding in the bushes. Several years later, Billy is told to put on a Santa suit for the kids at a toy store that he worked at after which he goes insane after he witnesses one of his coworkers possibly attempted to rape a female coworker, as it reminded Billy of how the killer Santa attempted to rape his mother.
He kills both the man and the woman, he then proceeds to kill the owner of the store and the assistant manager. He then proceeds to kill two teenagers that were having sex on a pool table and kills a teen that was sledding down a hill after Billy ran into the woods from the police when a few cops caught someone sneaking into the room of a little girl and it turns out it was a man pretending to be Santa Claus to surprise his daughter, they got the wrong person.
Billy plans to return to the orphanage he was put in after his parents were killed, possibly to get revenge on Mother Superior for the way she treated Billy when he was a kid. Billy manages to kill a police officer sent to the orphanage to look for him.
Billy was then shot twice in the back by the chief of police, killing him. After he died, his brother coldly looked up at Mother Superior and says "naughty", indicating that he plans on avenging his brother. And so, Ricky, would return in the next two sequels and begin a killing spree himself to avenge his brother.