Undertale Wiki

Beware of the man who speaks in hands.

River Person

W. D. Gaster was the royal scientist before Alphys, responsible for creating the CORE. Gaster's Followers relay various explanations as to what happened to Gaster. One iteration says that he "fell into his creation," another says that "his experiments went wrong," and the last one says he "shattered across time and space." Characters such as the River Person and Gaster's Followers hint at his existence. Similar to Sans and Papyrus, he speaks in a typeface different from the other characters.



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

Room 268 and 269

Surprised Mystery Man.

In Room 269 (room_mysteryman), a figure (spr_mysteryman) widely believed to be Gaster can be found. The figure is black and white with a distorted, cracked face. Unlike every other NPC, they have no collision physics, and interacting with them causes them to react in surprise and vanish while a sound effect plays.

This room can only be accessed when the game's fun value (which can be changed by editing file0 and undertale.ini) is set to 66. In this scenario, Room 268 (room_water_fakehallway), a hallway with a 10% chance to contain a gray door, appears between Room 94 (room_water_savepoint1) and Room 95 (room_water11), the rooms with the crystallized cheese and Sans's telescope, respectively. The door in this hallway leads to Room 269.

Once the protagonist leaves Room 269 back into Room 268, the door disappears from the corridor, though it is possible to exit the room and trigger the door's reappearance, as the fun values do not reset until the protagonist leaves the hall. The corridor itself becomes inaccessible once the protagonist leaves it and all values drop to 0.

Upon attempting to call someone using the Cell Phone in either of these rooms, the default message "There's no response..." appears.

Room 123

Room 123 (room_water_prebird) is a removed corridor with tall grass that is presumed to connect Room 99 (room_water_bird), where the bird that carries the protagonist over a disproportionately small gap is located, and Room 116 (room_water_friendlyhub), where the six-way fork in Waterfall is. The characters in this area mention that this corridor is a bug catching spot.

Room 123

An unknown character on the left side of the tall grass mentions that "there is somebody with a creepy smile behind you." The unseen character presumably disappears after the dialogue is triggered. The character with the "creepy smile" is possibly the Mystery Man seen in Room 269 which may be Gaster, and the evidence supporting this theory lies within the word "smile" in the dialogue, as the track that plays in entry 17 is named mus_smile. However, it could also be Flowey (who follows the protagonist throughout the game), Sans, or even the fallen human.

Room 272

Room 272

Room 272 is black and has a ghostly figure (nicknamed "Redacted", as the file name for it is spr_redacted_a) in the middle of it that becomes less transparent as the protagonist approaches. If the protagonist attempts a conversation with the NPC, it returns "* [redacted]" in lowercase Wingdings, which implies that a conversation was planned here but was removed for security purposes.[1] Exiting Room 272 leads to the Sound Test Room, where the protagonist can listen to four songs including Gaster's Theme.

All but one of the songs can be played and switched amongst each other. Upon playing Gaster's Theme, the other three songs are unable to be played again even if the player tries to do so. After Gaster's Theme is concluded, the text "Thanks for your feedback! Be seeing you soon!" is displayed and either the game crashes, or the protagonist is put in the room with the fishing pole in Snowdin, suggesting this room was intended to be focused on Gaster.

To access this room and avoid the Annoying Dog error screens, a hexadecimal editor needs to be used to change the "Dogcheck" value.[2]

The Stable

An unused sprite for the stable.

Inside the game's files are strings of text that implicate a stable was planned to be put into the game. There would be a trash can where a key can be found; if the key is brought to the horse stable, the same figure from Room 272 appears and says "* x" in Wingdings.

Main Story

Room 264

Entry Number Seventeen

In Room 264 (room_gaster), the text below is displayed in uppercase Wingdings. This text is believed to be the seventeenth entry from the True Lab that cannot be accessed. This could, however, only be a red herring, since another entry number 17 also exists, written by Alphys and very obviously connected to the other entries accessible in the True Lab. It is worth noting that both Alphys's seventeenth entry and Room 264 are inaccessible in normal gameplay – Alphys's entry can only be found in the game's text files, and Gaster's entry is only accessible through SAVE manipulation or debug mode. Room 264 immediately follows the generator room in the True Lab.

Transliteration of the Wingdings text is as follows:

  • DARK
  • VERY
  • VERY
  • ...

Once the message ends, the screen turns black for a second before the game closes. The audio that plays during the entry is labeled as "mus_smile" in the game files. This file can be sped up by 1000% to reveal Muffet's laugh, reversed, and then looped over.[3] An excerpt from the entry number 17 can also be found on a snapshot of deltarune.com/him.png from 2015.

"The Man who Speaks in Hands"

River Person screenshot hands.png

During one of the travels with River Person, they say "Beware of the man who speaks in hands." There is speculation that this alludes to Gaster since the typeface used in the entry number seventeen (room_gaster) uses hand symbols.

River Person screenshot other world.png

A similar line from the River Person is "Beware of the man who came from the other world." Considering the similarities it shares with the previous quote, it might either refer to Gaster or the monster So Sorry, whose check text reads "This creature is definitely in the wrong time and space!" as well as the file name of So Sorry's theme being mus_wrongworld.


Goner Kid

There is some inconclusive evidence as to whether Goner Kid is actually related to Gaster. Like Gaster's followers, Goner Kid's sprite has minor differences compared to the monster their sprite is based on. Goner Kid's clothing has a blocky, checkerboard-like pattern, they have a bow or two horns/spines on one side, two lines behind their head, and their eyes have no pupils. However, unlike Gaster's followers, the protagonist's phone works if they attempt to use their cell phone while in the room, and Goner Kid never mentions Gaster's name.

Gaster's Followers

The protagonist cannot call Papyrus while a Gaster follower is present, describing that the phone will not turn on.

Gaster's Followers are gray NPCs that are found near the elevators in Hotland when the fun variable is at a certain value. They all resemble certain NPCs in the game but with a few minor differences.

If the protagonist tries to call Papyrus (or Papyrus and Undyne) while in a room with a follower, they only get the line "The phone won't turn on." The protagonist can still attempt to reach Toriel over the phone. The phone works normally after leaving the room.

Goner Clam Girl

Goner Clam Girl, also known as Clam Goner, is a Waterfall NPC exclusive to the Nintendo Switch version of Undertale, where Clam Girl gets some new dialogue in the epilogue of the True Pacifist Route. At the final line of her dialogue, Clam Girl turns into Goner Clam Girl. She then disappears with the same sound effect as Mystery Man and Gaster Follower 2, which shows a possible connection to Gaster.


Sans is presumed to have a connection with W. D. Gaster due to the workshop behind his house and the name of his weapons used in the Genocide Route.

Goner Kid, the NPC that discusses alternate timelines, says, "An umbrella...? But it's not raining." This relates to one of Sans's leitmotifs "It's Raining Somewhere Else" which plays when he takes the protagonist out to dinner in the MTT Resort and in his workshop.

On the official Undertale Tumblr, is a post that includes the line "besides, it’s rude to talk about people that are listening, right?"[4] This quote is similar to a line from Gaster Follower 3.

Papyrus and Sans's House location workshop.png

Room 80 (room_tundra_sansbasement) is a workshop that has four drawers and a strange machine covered up with a curtain. One drawer contains a badge, and another contains a photo album with numerous people that the protagonist does not recognize. If the protagonist has encountered Clam Girl earlier in the route, interacting with the drawer causes a card to slip into the protagonist's view; it displays a poorly drawn picture of 3 people, with the words "don't forget" written on it. The other two drawers causes the protagonist to read the blueprint on the countertop, which is said to be written in unintelligible symbols or handwriting that could potentially be related to W. D. Gaster or Alphys, as she also writes in illegible handwriting, as shown in the note before entering the True Lab.[5]

The note written on the picture with three people is most likely from Sans; Unlike Papyrus, he does not write in his typeface, which can be seen when the protagonist reads the note on his treadmill.

In Room 264 in one of the parts of Gaster's version of Entry Number 17, he says, "What do you two think?" By "two," Gaster may be referring to Sans and Alphys, as it is hinted at the end of the True Pacifist Route that they had a past together and Gaster could be the missing link to where they possibly could have had a relationship.

A "Gaster Blaster" Sans uses in battle.

The broken machine in the room has been said to be unfixable according to Toby Fox.[6] This means that the machine was never meant to be fixed, and if this was the creation Gaster fell in, then he is surely doomed to remain erased.

Additionally, Sans uses a weapon during his fight in the Genocide Route called a "Gaster Blaster," possibly indicating that Gaster developed the weapon. Another theory could be that it was a weapon specifically made to be used against Gaster if he was a boss in the game.



  • "W. D. Gaster" is presumed to be a combination of the fonts "Wingdings" and "Aster."
    • W. D. Gaster's name could also be a reference to "M.D. Seeger," the alias of Shigeru Miyamoto used in the EarthBound end credits (as "Opening Rock Guitar").[7]
  • Attempting to name the fallen human "Gaster" causes the game to return to the intro.
    • In the PS4 and PS Vita versions, this would cause the game to crash. As of v1.03–4, it simply restarts the game.
  • If the protagonist's name is changed to "Gaster" through the SAVE files, the ability to reset becomes unavailable as the game restarts upon clicking the Reset button.

Examining a refrigerator in the True Lab while the room is still under mist triggers a description of a man believed to be W. D. Gaster

  • In the True Lab, if the protagonist does not activate the fans and enters the area where the protagonist encounters Snowdrake's Mother and interacts with the second refrigerator in the room, the narration describes a figure obscured by the fog in the shape of a man. This figure could be Gaster. However, it may simply be the "watching man"[8] Amalgamate that tucks the protagonist into bed in the True Lab.
    • It could also be the "Man" character from Deltarune, as he is described in a similar fashion.
  • The voice bites used in Room 264 (snd_wngdng1 through snd_wngdng7) are excerpts from the text-to-speech voices used in abc_123_a, possibly indicating a connection to Toby Fox or other meta-knowledge.
  • Alphys and Gaster both wrote an Entry Number 17; neither transcript appears without file manipulation.
  • If Entry Number 17 is considered, Gaster is the only individual character to have a unique typeface and soundbite without their face accompanying the text box when he talks. The other main-game examples of a unique soundbite but no dialogue portrait are Mettaton (during his initial form) and the species of Temmie, though they both keep the Determination Mono typeface.
  • The figure in Room 272 speaks with an asterisk and in lowercase, similar to Sans. Entry Number 17 is written in uppercase and without an asterisk, similar to Papyrus.
  • It is possible that Gaster could have created the DT Extraction Machine in the True Lab as Alphys admits to using blueprints to operate it in Entry Number 5.[9] This may be the blueprints found in Sans's Workshop.
  • On the official Undertale Tumblr, Sans suggests doing research about Shyren's lower body. Shyren's head and body are two different beings, but an optical illusion makes them look like one entity.[4]
    • This could relate to the face that shows up on the body of the Mystery Man. Further interpretation could be that the Mystery Man is actually two different monsters or an Amalgamate.
  • If Mystery Man is turned upside down, their clothing and hands resemble another face. Notably, before interaction, this face appears to be surprised, but after interaction, it appears calmer, contrary to Mystery Man's surprised expression.

The modified Uboa sprite used in the Halloween Hack.

  • Mystery Man shares some visual similarities with Uboa from Yume Nikki. This appearance is also shared with Dr. Andonuts from Toby's EarthBound Halloween Hack.
  • In the game files, Gaster's Theme is named mus_st_him, unlike the other rooms in the sound test that have their song names explicitly shown (such as mus_st_happytown).
  • snd_mysterygo uses the same piano sound as Gaster's Theme.
  • Until version 1.001, events related to Gaster were inaccessible unless a SAVE file was edited to have "fun" capitalized to "Fun."
  • In a tweet, Toby Fox showed very early concept art for Papyrus. In the same image was a note saying that Papyrus "had a * named *" with the nouns censored out. It is possible this refers to Gaster, due to the popular theory that Gaster is related to Sans and Papyrus in some way.[10] This note may also refer to Grandpa Semi.
  • The Gaster card is not included in the official Undertale tarot, which indicates that this card is either a spoiler or not canon. However, Toby Fox has stated the merchandise is not canon.

See Also


  1. Room 272
  2. Undertale – Disabling Dogcheck (The Annoying Dog Error Room) - YouTube
  3. W. D. GASTER "Mus_Smile" Dissected! - YouTube
  4. 4.0 4.1 for honesty’s sake, investigate the truth for yourself, then ask: how is this going to help people? besides, it’s rude to talk about people that are listening, right? not everyone is as tough as my brother. - undertale on Tumblr, October 05, 2015.
  5. (It's hard to read because of the handwriting, but you try your best...) - Alphys's note
  6. @rcrkar3 You've all seen the happiest outcome. Neither of them could fix the machine, no matter how hard they tried. No one can. - @FwugRadiation on Twitter, September 18, 2015. Archived on November 07, 2015.
  7. MOTHER 2 / EarthBound Factoids & Trivia - STARMEN.NET
  8. The sprite name for this character is spr_watchingman_0.
  9. I've done it. Using the blueprints, I've extracted it from the human SOULs. I believe this is what gives their SOULs the strength to persist after death. The will to keep living... The resolve to change fate. Let's call this power... "Determination." - True Lab, Entry Number 5
  10. (apparently) the genesis of papyrus - Toby Fox (@tobyfox) on Twitter, January 08, 2017.