Slester is a humanoid that resembles some form of doll.
Slester is a creepy 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. It is orange in color.
If player will stay idle while hiding under the desk for too long, and no suits will be during this time in Office, Slester will jumpscare the player. Slester's reflection can be seen every time while hiding.
Slester will only appear in the Office if the player hides for too long. It's presumed that Slester starts immediately right behind player's back, judging by it's reflection visible while under the desk.