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"☟♏●●□ ⧫♒♏❒♏📪 ☞❒♓⬧&📬"
– Decimal!Gaster

 Doctor W.D. Gaster is the previous royal scientist before Doctor Alphys. He speaks in a type face different from other characters. His text, what little there is, is in all caps similar to Papyrus. He was formerly the Forgotten Scientist until the total system crash.


Doctor Gaster is Frisk's caretaker and assists them in rebuilding their world by visitng different AUs. He is often referred to by Frisk as "Mr. Gaster". He often chats with the King and his wife about the status of the world. While both of the dreemurrs were hesistant at first. They eventually agreed with The Doctor's solution of travelling to different worlds and taking pieces of those worlds to rebuild the broken world. Frisk also agreed with Gaster on this solution. Gaster, himself, went through multiple theories before coming to this conclusion. He thought about having Frisk reset the timeline but that could potentially damage the world even more. He also thought about creating a machine to reverse the effects on the world's destruction. But there was nothing to go back to. Their world. The world they lived in was destroyed by a computer system crash. They have nothing go back to and this only pushed Gaster further to find a solution to he finally settled on the AU pieces plan.


In his stabilized form, Gaster has a black coat with a light grey sweater and light grey pants underneath as well as black shoes. In his unstabilized state, Gaster is just like his mysteryman appearance.


  • Gaster's stats are in the same as his actual battle stats from UNDERTALE.
  • Gaster loves spaghetti despite how he may deny it.
  • Gaster nearly lost himself to his madness for being lonely in the void so long. The system crash prevented this.
  • Gaster sees Frisk as a eager student who he's taken under his wing.
  • Decimal!Gaster's stable overworld and battle sprites were made by Beethovenus.

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