Board Thread:General Discussion/@comment-37195119-20181014185922/@comment-37446926-20181109174521

He is an Character found through Hacks,Other Characters found in the Same Way talk about Him,and they say he was the Old Royal Scientist,and that he Fell in the Core,his more Important Creation.

This is Everything Canon about Him,its Predictable that Toby Fox (The Creator of Undertale) has already forgotten about Gaster,as he can not be found by just Buying the Game and Playing it.

Gaster made an Appearence in DeltaRune (The New Game of Toby Fox,that has the same characters as Undertale.),and he can be found in Normal Ways,so Toby has remembered Gaster,but its Unknow if he will be Important in the other Chapters or just appear as this Easter Egg.