Brahms Heelshire is the titular antagonist of The Boy, portrayed by Jett Klyne (young) and James Russel (adult).
He was the son of a wealthy family called the Heelshires, and was also a serial killer.
He was a sociopathic child who was friends with a young girl named Emily Cribbs. When Brahms was 8 years old, he and Emily wandered into the woods by themselves, where Brahms then killed her for some unknown reason by smashing her head in. After which, he started a fire so as to fake his death and avoid punishment, which resulted in his face becoming horribly burned and scarred.
To protect their son, the Heelshires hid Brahms away in the walls of their mansion and had him declared dead so that no one could find him. Brahms then began wearing a porcelain doll-like mask so as to hide his multilated face.
His parents, who by then had grown terrified of him, hired countless nannies in an attempt to find someone to care for him. However, none of the nannies met his standards, and so he killed them all. Eventually, they found a nanny called Greta Evans that Brahms apparently liked, and so they were able to finally leave their house under the assumption that they were going on holiday, while leaving Brahms with her, when really they intended to kill themselves.
His parents apparently left Brahms with a “nanny” as a parting gift so that they could kill themselves while making sure he was cared for. He occupied himself by stalking Greta, moving the doll (that was supposed to portray him as a child) around the house.