History Characters / UndertaleSpoilerCharacters

* VoiceGrunting: The oddest sounding variety of it in the game: a jumble of text-to-speech voices speaking in gibberish, only heard in the hidden Entry #17. The text-to-speech voices are actually taken from a message asking dataminers who happen upon the file not to spoil the game's secrets, which is then jumbled up for Gaster's voice. The Version 1.01 patch replaced the message with the same text-to-speech voices [[LaughingMad laughing, one after the other]], which sounds pretty much the same when jumbled up.

* {{Leitmotif}}: [[https://www.youtube.com/watch?v=n0dgaYe2LZw "Gaster's Theme"]][[note]]"mus_him" in the game's files[[/note]], a song that can only be heard in a secret SoundTest screen that only features a few supposedly [[DummiedOut unused]] songs and locks up once the player reaches his theme. It's simply an eery arppegio played on a piano with some backing, so jury's out on whether any other arppegios in the soundtrack are meant to be quoting it.

A group of abominations created by accident from a terrible experiment involving Determination.

* [[invoked]]DummiedOut: Originally, ''all'' evidence of Gaster's existence was locked away in the game's files, unable to be accessed normally; players originally learned about him [[NoFourthWall by fixing a "typo" in the game's save file]] (changing the "fun" item to "Fun" and setting it to certain values). After a patch, the "typo" was corrected so the Fun value to worked properly, allowing much of the Gaster-related content to be accessed legitimately (albeit under very unlikely circumstances), including the Gaster Followers, the Goners, and the Mysteryman encounter. Some of it is still only found in the files however.

** W.D. Gaster and his followers are characters hidden in the game's code with an unclear identity. Some content related to him resides within (or is related to) late-game content in both routes. Granted, [[InvertedTrope you aren't really expected to find him yourself anyway]].

* AmbiguouslyEvil: The Old Tutu is described as being covered in dust (which is what monsters turn into when they die) and the Ballet Shoes make the player feel "incredibly dangerous" after putting them on. Thus, it's implied that their owner used them to kill at least one monster, possibly more. However, it's not known if they did this out of maliciousness or simply self-preservation, since the monsters were also trying to kill ''them''. It’s also possible the dust did not originate from any monster, instead it gathered naturally from being abandoned over the passage of time.

* AbstractApotheosis: As noted in SentientCosmicForce, you’re a being only visible in consequences that happen in the timelines, you are the driving force in the world, it’s your choices and determination that replaces Frisk's. Thus (if perhaps only in the “purity of action” sense of the trope or perhaps something more literal), you are not just a {{determinator}}, you are DETERMINATION itself.

* TheAntichrist: In the Genocide run. You fit the archetype regardless if you’re playing as Chara or not. A figure of unending destruction who helps bring about TheEndOfTheWorldAsWeKnowIt.

* AxCrazy: In the genocide run and the darker neutral runs, you are one of the biggest examples in videogame history; after all, name one character who tediously hunts down an entire country and kills them one by one, and if you choose to erase, destroys the entire gameworld. Emphasis more on the ax than the crazy, [[SubvertedTrope as in real life you’re likely much more sane and kind]], hopefully.

* {{Determinator}}: You have to be to get one of the true endings, or even make it to the end after all the deaths you’ll get; determination and the resolve to achieve what you want is one of the game’s main themes, and it’s heavily encouraged in players to match Frisk and the Fallen Child.

* SentientCosmicForce: An interpretation, as you’re a being only visible in consequences that happen in the timeline; you are the driving force in the world. It could be said that you are Frisk/Chara's DETERMINATION.

* SuperPoweredEvilSide: For Frisk, especially when you start killing literally everyone against Frisk's will; remember, Frisk is just a little kid who most likely would not want to hunt down and kill every single monster, and even if they did, being just a child they probably wouldn't have been able even if they tried. You’re the one fighting, the one dodging, and the one killing. In pacifist, you’re a much more benevolent SuperPoweredAlterEgo. In a very confusing double whammy, should you interpret Chara's speech as literal, Chara by the Genocide ending could be interpreted to be yours, an embodiment of everything destructive you've ever done in videogames [[EnemyWithout given life by your own hands]].

The enigmatic Dr. W.D. Gaster was the original Royal Scientist, before Dr. Alphys. Can't find him? Well, that’s because he’s not really around anymore. Originally, if one were to explore the game's files, they'd come across a few odd [=NPCs=], rooms, and messages that were cut. Eventually, some of it was reinserted into the game as incredibly hard to find easter eggs that depended on luck. If a player were to find these, what followed was the mysterious tale of a brilliant mind who fell into a creation of his that accidentally caused him to be shattered across reality, with his fate uncertain. Even to this day, no one knows the complete story of W.D. Gaster… well, no one that wants to talk, anyway.

* AmbiguouslyEvil: Gaster is certainly an ominous figure (see TheDreaded down below), but he doesn't actually ''do'' anything to suggest he's malicious. Due to just how unknown he is, its really impossible to discern his true nature or what, if any, plans he might have. He might be a bad guy, he might not. Then again…

** To Sans, thanks to his Gasterblasters and scientific interests, with this often extending to Papyrus via proxy. General consensus is that Sans knew Gaster, but the exact nature of their relationship is never addressed.

** Gaster's life was cut short, and he fell into his creation. But the followers never make clear if it was an accidental death because his experiment went wrong, [[DrivenToSuicide or one]] [[ThanatosGambit on purpose]] after his experiment went wrong. One of the followers wonder if Alphys will end up the same way, which [[{{Foreshadowing}} may be about her suicide in multiple neutral endings]]. This isn't even bringing up the possibility that he was ''pushed'' into the machine.
*** It's also not specified which "creation" he fell into. The most likely candidate is probably the CORE, since it's his only confirmed invention — but it's also unclear how a geothermal-powered magical electricity engine causes one to be [[invoked]][[DummiedOut scattered through time and space]], unless there is some detail about its operation we don't know about. Other candidates for his creation include the Determination Extraction Machine (found in Alphys' True Lab, but it's implied that she might have not been the one to design it) and the mysterious machine in Sans' secret room.
** Goner Kid asks Frisk about the prospect of a world where everything is exactly the same except you don't exist, yet with everything functioning perfectly without you. It can be inferred that this was also Gaster's fate, but it is ultimately unclear if this is supposed to be taken as [[RetGone the monsters legitimately not remembering he ever existed]], or just never mentioning him or talking about him. Him being an InUniverse exploration of a DummiedOut character supports the former, while his also InUniverse status as a ToughActToFollow supports the latter.

* [[invoked]]DummiedOut: Originally, ''all'' evidence of Gaster’s existence were locked away in the game’s files, unable to be accessed normally. A later patch corrected an error and allowed the game’s hidden Fun value to work properly, allowing a lot of it to be accessed (albeit under very unlikely circumstances) legitimately, including the Gaster Followers, the Goners, and the Mysteryman encounter. Some of it was still left in the files however.
** His Entry Number Seventeen report (Room 264, room_gaster) is completely inaccessible outside of hacking the game, as he details his “next experiment” to two unknown individuals. It is also a crucial piece of ProductionForeshadowing for ''Deltarune''. Its talk of darkness and the "garbage noise" that Gaster talks over are plot points in that game.
** room_water_redacted, or Room 272, is a blank, empty room with a mysterious figure in the middle of it. Regardless of whether the character itself has ties to Gaster (it only says a single word in Wingdings, being “[REDACTED]”), the room’s exit leads to the Sound Test, the one place in the game where you can listen to Gaster’s Theme.

* FailureIsTheOnlyOption: In a currently deleted tweet, Toby stated that [[https://twitter.com/tobyfox/status/644973310481166340 "You've all seen the happiest outcome. Neither of them could fix the machine, no matter how hard they tried. No one can."]]
* TheGhost: His existence is only vaguely hinted at through the game. Dr. Gaster was the previous royal scientist before Alphys, but his experiments have gotten him shattered across the time-space continuum. His predicament is so bad that players originally learned about him [[NoFourthWall by fixing a "typo" in the game's save file]] (changing the "fun" item to "Fun" and setting it to certain values; after a patch, changing it became unnecessary) and then trying to puzzle it out through data mining and trial and error.

* {{Leitmotif}}: [[https://www.youtube.com/watch?v=n0dgaYe2LZw "Gaster's Theme"]], a song that can only be heard in a secret SoundTest screen that only features a few apparently ''[[DummiedOut unused]]'' songs and locks up once the player gives "feedback" by listening to it. Due to its simplicity, it may be in several other songs and there’d be no way of knowing what was intentional and what wasn’t.

** The secret room 272 with the mysterious figure that says "redacted" in wingdings leads to a Sound Test, and the moment you put Gaster's theme, it will say "thank you for your feedback! Be seeing you soon!", which led to a supposed connection with a mysterious voice who was waiting for us in ''Deltarune''.
** The original version of ''Deltarune'''s website in [[https://web.archive.org/web/20160817183540/http://www.deltarune.com/ December 2015]], ''unnoticed by the entire player base back then'', was a pitch-black page with a hidden message in Wingdings that [[https://tcrf.net/Prerelease:Deltarune changed over time]]. First it quoted from Entry Number Seventeen, and then it had Gaster mentioning the legend of the three heroes who oppose the Angel's Heaven:

* RetGone: Some believe that, due to his name triggering a restart in the name select, the dialogue from the Goner Kid, and the lack of any characters ever mentioning him might imply that Gaster was not only shattered across space and time but had his history erased and no one remembers him. Of course, this is just one of many mysteries surrounding the man and no one knows for sure.

* ItsAWonderfulPlot: For poor Dr. Gaster, this trope appears to have gone horribly wrong; one of the grey [=NPCs=] asks the player about the prospect of a world where everything is exactly the same except you don't exist, yet with everything functioning perfectly without you. What's worse is that his creations weren't erased from history, and yet [[InSpiteOfANail life still went on]]. And it even seems to be worse than that; other [=NPCs=] needed to be coded or patched (by the v1.001 update) back into the game to get any information on him. Whatever happened was so bad it did the same to ''anyone who knew much about him''... except potentially for Sans, who wields weapons named after him, is implied to have researched a supposed ''[[LeaningOnTheFourthWall anomaly messing with timelines]]'' alongside him, and may or may not be related to him in some way or another.
* {{Leitmotif}}: [[https://www.youtube.com/watch?v=n0dgaYe2LZw "Gaster's Theme"]], a song that can only be heard in a secret SoundTest screen that only features a few apparently ''[[DummiedOut unused]]'' songs and locks up once the player gives "feedback" by listening to it. Fittingly enough, the vessel survey that opens ''Deltarune'' plays a remix of his theme.
* MeaningfulName: Named after the Wingdings font, which he uses to speak and write. Much like the man himself, Wingdings is cryptic and mysterious, and it takes a lot of effort to memorize and understand. "Gaster" probably comes from the Old English word "gast," from which the word "ghost" derives. "Aster" is also the name of a typeface and is a genus of flowers.

* RetGone: Apparently, whatever fate befell Gaster took his history with it, as even ''learning his name'' requires extreme luck and/or messing with the code.
* RiddleForTheAges: While there are some "models" of Gaster that are more popular in fanon interpretation, at the end of the day, he as a character is an absolute mystery on just about every level. We have no idea what he was like as a person, what his goals or relationships were, or even his exact fate and how it befell him; all that is known for certain about him is what his followers tell us (and that Sans has a weapon named after him).

* VaguenessIsComing: Among Alphys' reports, there is the elusive Entry #17 in which Gaster talks about doing research on an ever expanding darkness. He then asks what two unknown people think about it.
* VoiceGrunting: The oddest sounding variety of it in the game: a jumble of text-to-speech voices speaking in gibberish, only heard in the hidden Entry #17. The text-to-speech voices are actually delivering a message asking dataminers who happen upon the file not to spoil the game's secrets, which is then jumbled up for Gaster's voice. The Version 1.01 patch replaced the message with the same text-to-speech voices [[LaughingMad laughing, one after the other]], which sounds pretty much the same when jumbled up.

The man who speaks in hands. Dr. W.D. Gaster was the original royal scientist, before Dr. Alphys. Can't find him? Well, ''he didn't exist in the game at all for a while''. Originally, if one were to explore the game's files, they'd come across a few odd [=NPCs=], rooms, and messages that were cut. If a player decided to insert these aspects back into the game, what followed was the mysterious tale of a brilliant mind who invented a machine that accidentally caused him to be shattered across reality, with his fate uncertain. Even to this day, no one knows the complete story of W.D. Gaster… well, no one that wants to talk, anyway.

And note that the above instructions on how to activate him are in past tense because now you can access these previously cut elements randomly in the game without having to alter your game. A second Goner was also added in the Switch port, and a figure implied to be very close to him facilitated the reveal of ''Undertale''[='=]s successor, ''VideoGame/{{Deltarune}}'', with the game itself having a notable amount of nods to the mysterious scientist. [[RiddleForTheAges As for what this means, however…]]

* [[invoked]]DummiedOut: An examination of the horrors of this trope. Gaster is lost through the game's files, unable to interact with anyone and aware that life goes on without him as if he's [[RetGone never existed]]. Players can search for him, but there's no way to help and so they can only wonder WhatCouldHaveBeen if Gaster wasn't so unfortunate to be a cut character. A patch later made it so the Fun events work without needing to capitalize "fun" in the save file, but there're no new ways to interact with him yet.
** His Entry Number Seventeen report in particular is completely inaccessible outside of hacking the game, which is interesting because it is a crucial piece of ProductionForeshadowing for ''Deltarune''. Its talk of darkness and the "garbage noise" that Gaster talks over are plot points in that game.

** The Memoryheads resemble [[VideoGame/EarthBound Giygas]].

* YouCannotGraspTheTrueForm: Definitely gives off these vibes, especially since their battle music [[VideoGame/EarthBound takes a sample from the]] TropeNamer. For example, before reaching Spare conditions, Reaper Bird's name is given as a single comma, and the Memoryheads are completely incomprehensible unless communicated to through your ''cell phone''.

** ''You'', as in, being a separate entity from the actual player character, spoils the fourth wall breaking aspects of the Pacifist and Genocide endings
** W.D. Gaster and his followers are characters hidden in the game's code with an unclear identity. Some content related to him resides within (or is related to) lategame content in both routes. Granted, [[InvertedTrope you aren't really expected to find him yourself anyway]].

* AssholeVictim: Maybe some of them. It's implied that at least a couple of them managed to rack up a lot of EXP and some LOVE before they were killed, most prominently the blue soul (whose items are described as "dangerous" and covered in dust[[note]]what monsters turn into when they die[[/note]]) and the yellow soul (who had a real gun). It's left ambiguous, however, if they did this for actually malicious reasons, or if they did it out of (legitimate, since unlike the player character they only have one life) self-defense, or a desperation to avoid being killed and forcibly used as a weapon to destroy everyone they love.

* OurSoulsAreDifferent: Humans in life, [[TheFairFolk unlike monsters]], are mostly physical matter, making them generally much stronger than an equivalent monster. Their colored [=SOULs=] linger after death whereas monster white [=SOULs=] vanish instantly (apart from those of 'boss monsters' like Toriel and Asgore). This asymmetry on their natures means it's ''almost impossible'' for a human to absorb a monster's SOUL but a monster can easily consume a lingering human SOUL, and use them [[SoulPower as an immense power source]]. Absorbing just seven [=SOULs=] (of which are obviously plentiful in supply), (Possibly) negates any AssimilationBackfire and would make that monster [[PhysicalGod become God-like]]. When Monster-Human relationships deteriorated in the prologue, and a war happened monsters lost. After the war eventually culminated in the banishment of monsters into the underworld, the despairing monsters can only hope their king one day acquires enough [=SOULs=] to shatter the barrier.

* HopeSpot: Possibly implied--there is a message in the CORE that implies the cyan SOUL may have made it farther then some think. The message reads, "(I cannot fight. I cannot think.) (But with patience, I will make my way through.)"

** Goner Kid asks Frisk about the prospect of a world where everything is exactly the same except you don't exist, yet with everything functioning perfectly without you. It can be inferred that this was also Gaster's fate, but it is ultimately unclear if this is supposed to be taken as [[RetGone the monsters legitimately not remembering he ever existed]], or just never mentioning him or talking about him.

* BlueAndOrangeMorality: There's a creature in the game's canon that exists outside the universe. This creature can't manifest into the world by itself, but [[DemonicPossession it can take control of a host and puppet them around]]. Whether it [[GoldenEnding befriends everyone] or commits systematic genocide, this creature does it [[ForScience just to see what will happen]]. [[RippleEffectProofMemory It remembers everything that's been done to it, in all timelines]], even when [[ResurrectiveImmortality their host body has been destroyed numerous times]]. What is this creature? It's you.

* BlueAndOrangeMorality: There's a creature in the game's canon that exists outside the universe. This creature can't manifest into the world by itself, but [[DemonicPossession it can take control of a host and puppet them around]]. Whether it [[GoldenEnding befriends everyone]] or [[KillEmAll commits systematic genocide]], this creature does it [[ForScience just to see what will happen]]. [[RippleEffectProofMemory It remembers everything that's been done to it, in all timelines]], even when [[ResurrectiveImmortality their host body has been destroyed numerous times]]. What is this creature? It's you.

* WeaponOfChoice: The Toy Knife, a knife made of plastic, which is said to be "a rarity nowadays."

* WeaponOfChoice: The Tough Glove, "a worn pink leather glove for five-fingered folk."

* WeaponOfChoice: The Ballet Shoes, which make you feel "incredibly dangerous."

* WeaponOfChoice: The Torn Notebook, which "contains illegible scrawls."

* FryingPanOfDoom: The Burnt Pan, which adds +10 AT and heals 4 more HP every time a consumable item is used.

* WeaponOfChoice: The Burnt Pan, whose "damage is rather consistent."

* WeaponOfChoice: The Empty Gun, described as "an antique revolver that must be used precisely, or damage will be low."

* FeatheredFiend: The [[NamesToRunAwayFromReallyFast aptly-named Reaper Bird]] Amalgamate is just one of the many who attack you in the True Lab. Ironically, it has no bird monster as a component whatsoever (not like there are many of those in the Underground to begin with).[[note]]It's made of [[AmphibianAssault Final Froggit]], Whimsalot, and [[{{Cyclops}} Astigmatism.]][[/note]]

* OurSoulsAreDifferent: Humans in life, [[TheFairFolk unlike monsters]], are mostly physical matter, making them generally much stronger than an equivalent monster. Their colored [=SOULs=] linger after death whereas monster white [=SOULs=] vanish instantly (apart from those of 'boss monsters' like Toriel and Asgore). This asymmetry on their natures means it's ''almost impossible'' for a human to absorb a monster's SOUL, but Monster-Human relationships deteriorated in the prologue, when discovered a monster can easily consume a lingering human SOUL, and use them [[SoulPower as an immense power source]]. Absorbing just seven [=SOULs=] (of which are obviously plentiful in supply), negates any AssimilationBackfire and would make that monster [[PhysicalGod become God-like]]. Fearing a preemptive strike, mankind attacked first, eventually culminating in the banishment of monsters into the underworld. Now the despairing monsters can only hope their king one day acquires enough [=SOULs=] to shatter the barrier.

* UltimateEvil: You can become this if you try hard enough. The Fallen will attempt to take this title from you at the end of the first No Mercy run, but if you're cruel enough over subsequent runs, they will eventually give up on out-eviling you. Notably, the Fallen is outright confused at how you could possibly be eviler then them even while admitting it's true. Also true in a more specific sense as, being the player, of course you don't show up in the game.

* OurSoulsAreDifferent: Humans in life, [[TheFairFolk unlike monsters]], are mostly physical matter, making them generally much stronger than an equivalent monster. Their colored [=SOULs=] linger after death whereas monster white [=SOULs=] vanish instantly [[spoiler: (apart from those of 'boss monsters' like Toriel and Asgore)]]. This asymmetry on their natures means it's ''almost impossible'' for a human to absorb a monster's SOUL, but Monster-Human relationships deteriorated in the prologue, when discovered a monster can easily consume a lingering human SOUL, and use them [[SoulPower as an immense power source]]. Absorbing just seven [=SOULs=] (of which are obviously plentiful in supply), negates any AssimilationBackfire and would make that monster [[PhysicalGod become God-like]]. Fearing a preemptive strike, mankind attacked first, eventually culminating in the banishment of monsters into the underworld. Now the despairing monsters can only hope their king one day acquires enough [=SOULs=] to shatter the barrier.

* OurSoulsAreDifferent: Humans in life, [[TheFairFolk unlike monsters]], are mostly physical matter, making them generally much stronger than an equivalent monster. Their colored [=SOULs=] linger after death whereas monster white [=SOULs=] vanish instantly [[spoiler: (apart from those of 'boss monsters' like Toriel and Asgore)]]. This asymmetry on their natures means it's ''almost impossible'' for a human to absorb a monster's SOUL, but Monster-Human relationships deteriorated in the prologue, when discovered a monster can easily consume a lingering human SOUL, and use them [[SoulPower as an immense power source]]. Absorbing just seven [=SOULs=] (of which are obviously plentiful in supply), negates any AssimulationBackfire and would make that monster [[PhysicalGod become God-like]]. Fearing a preemptive strike, mankind attacked first, eventually culminating in the banishment of monsters into the underworld. Now the despairing monsters can only hope their king one day acquires enough [=SOULs=] to shatter the barrier.

* OurSoulsAreDifferent: Humans in life, [[TheFairFolk unlike monsters]], are mostly physical matter, making them generally much stronger than an equivalent monster. Their colored SOULs linger after death whereas monster white SOULs vanish instantly [[spoiler: (apart from those of 'boss monsters' like Toriel and Asgore)]]. This asymmetry on their natures means it's ''almost impossible'' for a human to absorb a monster's SOUL, but Monster-Human relationships deteriorated in the prologue, when discovered a monster can easily consume a lingering human SOUL, and use them [[SoulPower as an immense power source]]. Absorbing just seven SOULs (of which are obviously plentiful in supply), negates any AssimulationBackfire and would make that monster [[PhysicalGod become God-like]]. Fearing a preemptive strike, mankind attacked first, eventually culminating in the banishment of monsters into the underworld. Now the despairing monsters can only hope their king one day acquires enough SOULs to shatter the barrier.

* AmbiguouslyEvil: The Old Tutu is described as being covered in dust (which is what monsters turn into when they die) and the Ballet Shoes make the player feel "incredibly dangerous" after putting them on. Thus, it's implied that their owner used them to kill at least one monster, possibly more. However, it's not known if they did this out of maliciousness or simply self-preservation, since the monsters were also trying to kill ''them''.

* PureIsNotGood: Your [[ArcWords determination]] ''will'' need the Japanese virtue of Makoto if you want to get an specific ending; this includes the [[OmnicidalManiac Genocide Run]]. Sans says this evil purity is the most dangerous part of you.

* RealityWarper: You can delete and edit the game's files, which clearly makes you this in a meta way, and, as said everywhere else, ''Undertale'' is a very meta game on purpose — then there's the ability to reset…

* TimeMaster: In this game, resetting and reloading are real, in-universe things.

* LogicalWeakness: Their items increase MercyInvincibility for a longer period of time, which means you have to deliberately take damage in order to make the best use of them...which will not be easy on a True Pacifist playthrough, since you only have 20 HP to spare.

* AxCrazy: [[UpToEleven Hoo]] [[OmnicidalManiac boy…]] In the genocide run and the darker neutral runs, you are one of the biggest examples in videogame history; after all, name one character who tediously hunts down an entire country and kills them one by one, and if you choose to erase, destroys the entire gameworld. [[Anime/DragonBallZ Majin Buu]] and [[VideoGame/MegaManZero Omega]] would be proud. Emphasis more on the ax than the crazy, [[SubvertedTrope as in real life you’re likely much more sane and kind]], hopefully.

*** It's also not specified which "creation" he fell into. The most likely candidate is probably the CORE, since it's his only confirmed invention — but it's also unclear how a geothermal-powered magical electricity engine causes one to be [[invoked]][[DummiedOut scattered through time and space]], unless there is some detail about its operation we don't know yet. Other candidates for his creation include the Determination Extraction Machine (found in Alphys' True Lab, but it's implied that she might have not been the one to design it) and the mysterious machine in Sans' secret room.
** One of the grey [=NPCs=] asks Frisk about the prospect of a world where everything is exactly the same except you don't exist, yet with everything functioning perfectly without you. It can be inferred that this was also Gaster's fate, but it is ultimately unclear if this is supposed to be taken as the monsters legitimately not remembering he ever existed, or just never mentioning him or talking about him.
** Whether the Riverperson's warnings about "the man who speaks in hands" and/or "the man who came from the other world" refer to Gaster is questionable. He is the most likely candidate for both quotes, as his speech relies in [[PaintingTheMedium hand signals]] and he doesn't reside in the world of ''Undertale'', but there are issues with this. For the former, not every symbol Gaster uses is a hand. For the latter, well, Gaster isn't really ''from'' another world as far as we know, he's just not in this one.
* AndIMustScream: Implied. One of the Goners you find talks about horrible it is that the world moves on without you but still looks exactly the same, as if you never mattered. And since the followers and the goners are implied to be connected in some fashion, it's not too much of a stretch to assume that Gaster is suffering from his "scattered across time and space" situation.

* [[invoked]]DummiedOut: An examination of the horrors of this trope. Gaster is lost through the game's files, unable to interact with anyone and aware that life goes on without him as if he's [[RetGone never existed.]] Players can search for him, but there's no way to help and so they can only wonder WhatCouldHaveBeen if Gaster wasn't so unfortunate to be a cut character. A patch later made it so the Fun events work without needing to capitalize "fun" in the save file, but there're no new ways to interact with him yet. In addition, there is the actual cut character Grandpa Semi. His name (found in the ''Undertale'' demo's code) is all we know, but since "Semi" could refer to semi-serif fonts, many think he is a proto-Gaster.
** His Entry Number Seventeen report in particular is completely inaccessible outside of hacking the game, which is interesting because it is a crucial piece of ProductionForeshadowing for ''Deltarune''. Its talk of darkness and the "garbage noise" that Gaster talks over are recurring plot points in that game.

* ThrowtheDogABone: Talking to him while holding an umbrella makes him feel less miserable about his situation.