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Grandma Calibri (Also known as Experiment #16) was an experiment created by Dr. W.D. Gaster to test the effects of the CORE on a living monster. Asgore refused to use a pre-living monster, for obvious reasons. So, Calibri was created. However, Gaster failed to create a SOUL for the monster, and it became SOULless. Calibri made up an identity for itself, and called itself Grandma Calibri. Eventually, the day came, and Grandma Calibri was thrown into the CORE. Because Calibri did not have a SOUL, all the atoms in her body spread apart all over the Underground. However, if certain temperatures are perfect, and humidity is low...

She just might appear.


Grandma Calibri enjoys people freaking out upon seeing her. She mainly avoids interaction, but will sometimes engage in conversation with another person sporadically. When she does, she usually talks about her hate for Gaster. She generally does not do anything else. When attacking (Although rarely), she sends out small chunks of herself as bullets. They dissipate, and reappear in Grandma Calibri's Body.

She is insane.



  • No one
    • Due to being locked in a cell for her entire short life, she never met anyone besides Gaster. She also could not care or truly be friendly with people, because she is lacking a SOUL.


  • Grillby
    • Grandma Calibri usually appears in Grillby's, due to the low humidity and dry air. She usually appears after hours however. She only knows Grillby by face, and both seem to not mind the other being there.


  • W.D. Gaster
    • W.D. Gaster is her enemy, due to tossing her in the CORE. She wanted nothing more then to see him suffer.
  • Asgore
    • Asgore was the one who ordered her creation and tossing into the CORE, and Calibri also wanted revenge on him.


Her statistics stay the same for each route.

HP 9999

ACTs: Check, Talk, Blow.

She cannot be hit, but she can be rendered neutralized by changing the temperature or humidity. This will cause her not to be able to manifest, and will dissipate back to her "Limbo" state.


"Dry air touches your lips." -Encounter
"The air is still." -Encounter
"It's dry." - Neutral Flavor Text
"It seems to come from the void" - Neutral Flavor Text
"It seems familiar." - Check Text
"You try talking to it. It doesn't respond" - Talk #1
"You talk to it again. It glances in your direction." - Talk #2
"You talk to it a third time. It smiles at you. Suddenly, it disappears!" - Talk #3
"You blow on the monster. It's body starts to wave a bit." - Blow #1
"You blow on it again, harder. It body seems to split apart and come back together." - Blow #2
"You blow on it with all your might. It splits apart!" - Blow #3

In order to "Spare" it, the you must perform the following ACTs: Talk x3/Blow x3.

Grandma Calibri will generally mention a man named Wilson, and confuse them with the person they are talking to. The reason for this is unknown. She speaks in the Calibri font.


  • Grandma Calibri is based off of a scrapped character from Undertale named "Grandpa Semi". It's theorized to be the grandfather of Sans and Papyrus.
    • "Semi" is part of a font, similar to how "Sans" is part of a font. Calibri is also a font.
  • Grandma Calibri's name was originally Grandma Georgia.
    • Georgia is a font as well.
  • There was an hour debate on Live!Chat on whether Grandpa Semi was canon or not, until The Haze3456 said it was. If it was not, then this page would be Grandpa Semi instead of Grandma Calibri.
  • For an unknown reason, Harcules is the only person Grandma Calibri does not call "Wilson", but instead calls him BH.