Yallew is a nick-name for one of the monsters.
Yallew is a monster similar to all the other monsters, except with a different jaw. Yallew has a jaw that has 3 teeth, two on the top and one at the bottom. However, there are strings attached to Yallew's tounge come and droop down, hiding the third tooth. But this third tooth can bee seen when in the jumpscare of Yallew in ESCaPE 2. There are also strings coming from Yallew's eyes that might resemble red skin.
Yallew's behavior is a lot like the other monsters, but Yallew is the slowest monster in the game (ESCaPE 2).
Yallew's Jump-scare is a lot like the other monsters too, with it's arms spread out in the shape of a T, and it's jaw wide open.