In The Maze Cutter, Billy is confirmed to have died of unknown causes sometime during the 73 year gap between the Death Cure and The Maze Cutter.
Billy was one of the Gladers in the Glade and he was also the Keeper of the Baggers. Billy was seen several times throughout the film and wasn't much of a talker. When Minho arrives with Alby outside of the Maze, Billy, along with the other Gladers, start shouting to them to hurry up. Right as Thomas runs into the Maze after Minho and Alby, Billy, along with the other Gladers, try to grab him and stop him from running inside, but can't grab or convince him to stay. The next day, when Thomas and Minho arrive with Alby, Billy runs to the doors along with the other Gladers to greet them and congratulate them. Later on, Billy is seen at the meeting just before Teresa arrives. At night, during the Griever attack, Billy is seen running to the doors with a group of Gladers to see why they aren't closing. Once they get there, the other doors around the Glade start to open as well and Billy looks in shock and terror. Once the Grievers start to show up, Billy runs off to the tall grass carrying a torch along with with Thomas, Teresa, Zart, Jack, and Mike. While hiding in the tall grass, they hear a Glader getting killed near them and soon after watch Zart get killed by a Griever. They run off to go find Alby, who is being escorted to safety by Jeff and Clint. Once they meet up with the Gladers that were hiding in the forest, they get attacked by a Griever. Billy, along with the other Gladers, run off to safety. The next morning, Billy is among the surviving Gladers who join Thomas and the others in escaping the Maze. He ends up making it to the end and escapes on the helicopter with the rest of the group. He then disappears in the transition to the Scorch Trials film.
In the Death Cure film, the name Bill is engraved on the Memorial Rock along with the names of others killed in the war against WCKD. It is not confirmed if this is him or if this is a different person.
- When the Gladers are running up to the doors to investigate them, Billy is seen jogging up without a torch. However, the next scene, he is seen running up to the doors with a torch.
- Billy was the only member of the main group to not make an appearance in the second film. This is because Landon Hazel, Billy's actor had personal issues and couldn't make it to filming.