After saving your past self from your fears, you overcome them by destroying The Thing, representative of fear itself. The Thing became not only an obstacle of the player in the basement though, but it is also the final boss, from which you need to protect your younger self from being overcome by The Thing. In the full game, it is also in the basement, forcing you to use your Fear Supermarket ability to progress. These fears are represented with the scenes they are resembled by, with The Thing watching nearby. In the full game, after you beat the Giant Neighbor boss in the Act Finale, you go to the Fear Hall, where you see all of Theodore's fears. In Beta 3, it can be found in the basement. In Beta 1 - 2, it can be seen outside the window in Fear Supermarket and Factory. It can also be seen in Fear Darkness behind the map. It first appears in Alpha 4, in a cutscene with a broken phonograph, the actions of which take place on the behalf of Theodore Peterson, where he covers his eyes with his hands while The Thing comes into the room. Standing still, The Thing often moves hands, torso, legs, and head. it continuously changes its shape, as its limbs become much thinner, then on the contrary - thicker. It is all black with two bright white glowing eyes.

In the betas to the full game, The Thing has an actual model.

This rendition of The Thing seemed much shorter than the player and seemed to have a large bundle of curly/messy hair. In the Alpha 3 build of Hello Neighbor, prior to the full game, The Thing appeared as a two-dimensional figure that could've only be seen using cheats or certain camera angles.

Hello neighbor beta 3 end