Old Nick

Old Nick is the sole antagonist of the 2015 independent drama film Room, which was based on Emma Donoghue's novel of the same name. He is a criminal who kidnapped and raped Joy "Ma" Newsome in captivity and biological father to Jack. He is portrayed by Sean Bridgers.

About
Old Nick lured 17-year old Joy Newsome by pretending that his dog was lost before kidnapping her and holding her captive in his garden shed. He raped and abused her for a period of time which resulted in the birth of Jack's deceased brother. One year later Jack was born, Joy tried to protect him fearing that Old Nick would killed them if his neighbors found out. Old Nick tells Joy that he has lost his job and threatens that he may not be able to afford their supplies in the future. To save Jack and herself, Joy trained him to pretend to be dead so Old Nick will take him to the grave. As a result Old Nick tried to strangle Joy almost to death

Eventually Jack escaped from the trunk and rushed to a man who mistake him for a girl and police arrested Old Nick for kidnapped thus Joy was saved and reunited with her family and son.

Old Nick suffered abuse from prisoners or possible victims of Old Nick that testified against him

Trivia

 * Old Nick is based off of Josef Friztl, Ariel Castro and Phillip Garrido, three men who kidnapped their victims and held them captive for years, and making them have children in the process.
 * Old Nick is another name for Satan. Even Emma Donoghue stated that the book is like "a battle between Mary and the Devil for baby Jesus."