W. D. Gaster
Spr mysteryman 0
Intro None
Type Teleporter
Signs of nearing Alert sound
Weird sound effects
Origin Undertale
Map(s) Special boss
Theme song Gaster's Theme
Partners None
Stunnable? No

W. D. Gaster is a boss in Slender Fortress.


W. D. Gaster was the royal scientist before Alphys, and responsible for creating the CORE. His life was cut short when he fell into "his creation". His existence is only hinted by characters such as the River Person and Gaster's followers. Similar to Sans and Papyrus, he speaks in a typeface different from other characters, and wholly in capital letters like Papyrus.

W. D. Gaster does not have a known official form, but there are several rooms and unused assets found in Waterfall that point to what he may have looked like.

In Slender FortressEdit

W. D. Gaster functions the same as Weeping Angels but a bit stronger, blinking doesn't break what Gaster considers observation, making him a very easy boss as all you have to do is look at him until you get out of his sight. He acts like The Sisters and Freddy Fazbear that he do not move when you are looking at him, but you can also die from staring too long. In order to get rid of him when you are alone, stare at him for 3 seconds or until you get static starting up, then look away or hide. W. D. Gaster occasionally will make an image and a sound play when he teleport around you.



  • Gaster's jumpscare was used from the Undertale fangame, "Slendertale".