William Afton and Henry Emily opened a restaurant around the early 70s, named Fredbear's Family Diner, which quickly evolved into a chain of restaurants known as "Freddy Fazbear's Pizza," started in 1983, under the company of Fazbear Entertainment, Inc. At some point, both of them left the company, with an unknown individual taking over as CEO.

William was secretly a serial killer, using mascot costumes to lure, abduct, and murder kids. His motives aren't known, though widely speculated to be him trying to achieve immortality through researching the paranormal, haunted metal (known as remnant), which he created through the murders.

His first target was Charlotte Emily, the daughter of Henry. She became the Marionette, a ghost who took care of and helped awaken the other lost souls.

In 1983, William's younger son also died in an incident, at the fault of his eldest — Michael. The younger son (name unknown, BV for short) 's fate is still unknown.