Slester is a humanoid that resembles some form of doll, presumebly a voodoo doll.
Slester is a humanoid that resembles a voodoo doll of sorts with big empty eyes and a droopy mouth with what appears to be suture marks on its chest and stomach, it could also resemble a Haniwa which are terracotta clay figures that were buried with the dead in Japan between the 3rd and 6th centuries. It also appears to have two needles through its body, one going through its shoulders, and the other through its head.
Slester does not appear in this version of the game.
Slester will begin on Night 4. He will appear at random while looking at the cameras. Staring at him for too long will cause him to shut off the power, forcing the player to do what they'd normally do when the power is off.