Name

Name the fallen human.

Naming prompt

At the beginning of Undertale, the player is given the choice of naming the fallen human. While the narrative flow and naming screen is seemingly the player naming the protagonist, it is to name the first human who fell into the underground.

Normally, the game asks "Is this name correct?" when asking for confirmation of the name. However, some names trigger a unique response, can have a different impact on gameplay, and certain major character names cannot be used. There is a six-character limit, but this can be bypassed by modifying the game files.

Once confirmed, the name appears as the SAVE file name, and is mentioned in certain situations. The protagonist's name is not revealed until they introduce themselves to the other characters in the True Pacifist Route epilogue.

All names (except "Frisk", as changing that name is required to leave Hard Mode) cannot be changed without performing a True Reset or completing a Genocide Route. On the Main Menu, the message "A name has already been chosen" appears when "Reset" is selected.

Names with custom responses

Below are listed names that give a custom response, replacing the default one. Alphabetic characters are case-insensitive and kana are script-insensitive. When played in Japanese, due to being able to enter both kana and alphabetic characters, the same response occurs regardless of whether the English or Japanese name was entered.

Forbidden

English	Japanese	Response
(Blank name)	—	"You must choose a name."
Alphys	アルフィー	"D-don't do that."
Asgore	アズゴア	"You cannot."
Asriel	アズリエル	"..."
Flowey	フラウィ	"I already CHOSE that name."
Gaster	ガスター
Sans	サンズ	"nope."
Toriel	トリエル	"I think you should think of your own name, my child."
Undyne	アンダイン	"Get your OWN name!"

Allowed

English	Japanese	Response
Frisk	フリスク	"WARNING: This name will make your life hell. Proceed anyway?"
Murder Mercy	ころす みのがす	"That's a little on-the-nose, isn't it...?"
AAAAAA	ああああああ	"Not very creative...?"
Aaron	アーロン	"Is this name correct? ;)"
Alphy	アルっち	"Uh... OK?"
Catty	キャッティ	"Bratty! Bratty! That's MY name!"
Bratty	アリゲッティ	"Like, OK I guess."
Bpants	バガパン	"You are really scraping the bottom of the barrel."
Chara	キャラ	"The true name."
Gerson	ガーソン	"Wah ha ha! Why not?"
Jerry	ジェリー	"Jerry."
Metta Mett Mtt	メタトン メタ	"OOOOH!!! ARE YOU PROMOTING MY BRAND?"
Napsta Blooky	ナプスタ ブルっち	"............ (They're powerless to stop you.)"
Papyru	パピルス	"I'LL ALLOW IT!!!!"
Shyren	シャイレーン	"...?"
Temmie	テミー	"hOI!"
Woshua	ウォッシュア	"Clean name."

Names with other effects

• Drak, Gigi, or Gugu — The Steak in the Shape of Mettaton's Face shows up as "FSteak" instead of "FaceSteak". This name is a reference to Gigidigi's webcomic Hiimdaisy. Gigi contributed work to Undertale.
• Gaster or ガスター — The game reloads to the prologue cutscenes as soon as the last character of "Gaster" is entered.
• Frisk or フリスク — In addition to having a custom response, this name activates Hard Mode.

Name in-game

The name being mentioned at a mirror.

The selected name is visible on the Main Menu, the SAVE file from SAVE Points, most encounters, the overworld menu, and when looking at Stats.

This name is also mentioned by various characters: Flowey, Asriel, Asgore in the Game Over screen, the dream sequences in Toriel's Home and Waterfall, and the fallen human's coffin.

In the True Pacifist Route, the name is mentioned in the VHS tapes in the True Lab. In Genocide Route, the name is mentioned when inspecting the mirrors in Toriel's Home, Asgore's Home, and the Lab console.

In contrast, the name is absent in Flowey's encounters, the New Home story expositions from monsters and Flowey, and the battle with Omega Flowey.

Changing the name in the SAVE files

Stats screen after editing the name to be 6 or more characters long

Normally, the name cannot be changed except after a True Reset or after a Genocide Route. However, it is possible to change the name during gameplay by modifying the game data. The following instructions are only applicable to PC versions.

1. Open the app data directory for Undertale. On Windows, this should be %LOCALAPPDATA%\UNDERTALE (typically resolving to C:\Users\USERNAME\AppData\Local\UNDERTALE, where USERNAME is the name of the Windows user). On macOS, this should be ~/Library/Application Support/com.tobyfox.undertale/, and on Linux it should be ~/.config/UNDERTALE/.
2. Open the file named file0 in a text editor.
3. The name is stored on the first line—replace it with a new name.

Numbers and symbols can be added to this new name. If it is longer than six characters, it covers surrounding text, and the text "Easy to change, huh?" appears in the Stats menu. Using a forbidden name has no effect.

The name is also stored in undertale.ini, which is where the name displayed when loading a SAVE file is retrieved from; however, it is overwritten with the name from file0 when the game is saved (if they differ). If the game is reset instead of loading a SAVE, the undertale.ini name overwrites the file0 name instead.

Trivia

• All forbidden names can be used in the Undertale Demo.
• If the protagonist's name is changed to "Gaster" through the SAVE files, the ability to reset is unavailable as the game restarts upon clicking the Reset button.
• On PC versions until v1.05, when attempting to name the protagonist "Gaster", the game reloads the title sequence after pressing the confirm button.
• On the PlayStation 4/Vita and Nintendo Switch versions until v1.03-4, the game crashed and displayed an error message as the last character of "Gaster" is entered.