Undertale Characters Guide


Undertale has been praised for several reasons over its near-decade tenure as one of the most influential indie games ever. Above all else, though, the game’s story — and its fantastic cast of characters — is its most valuable contribution to the video game landscape.

I’ve played the game many (many) times over, and I’ve enjoyed pouring over the lore and theories to explore the personalities and motivations of each character. I’ve written this Undertale Characters guide as your definitive article for everything you could want to know about the underworld’s inhabitants: it aims to give you a deeper understanding of the incredible world Toby Fox created and explore why these NPCs are still fervidly discussed to this day.


Bottom Line Up Front

Before reading on, I highly recommend you complete the game at least once — there will be spoilers ahead.

Except for Chara and Asriel, I should also note that I won’t include the various different fates of each character as determined by the conclusion of different paths (Genocide, Neutral, and True Pacifist). The entry for each character will provide a backstory so that you can understand their personality types and motivations; that way, the logic behind their fates on subsequent runs should then be clear when you play through without having to spoil anything!

  • The main characters included in this guide are Frisk, Sans, Papyrus, Undyne, Alphys, Napstablook, Chara, Asriel, Mettaton, W.D. Gaster, Toriel, Muffet, Flowey, and Asgore.
  • Not all main characters in Undertale reside in Underground: many important beings exist outside the realms of the physical world.
  • If you’re in a rush and/or don’t want to risk anything being spoiled, make sure to still check out the frequently asked questions section for some insights you might not know.
  • The Some notes on the world section below will also help add context without spoiling anything. Read this if you require a quick primer before beating the game, and then come back when you’ve finished it.
  • If you’re interested in a deeper exploration of a certain character, be sure to click their name for a link to one of our specific character guides.

The Characters


Undertale Characters frisk

  • Creature type: Human
  • Role: Protagonist
  • Skills and abilities: Determination, respawning, and saving
  • Fallen human number: 8
  • Gender: Ambiguous

Oddly enough, our protagonist has one of the smallest backstories of any character in Undertale. Our player character is a young boy who stumbled down a hole leading him to the monster underworld: Frisk is his canonical name, with the player’s name reserved for another we’ll discuss later.

Frisk is more of a vessel for the player and their actions rather than a deeply written character. They don’t have a specified gender and are only described as they or human throughout the game. They are the eighth child (and eighth sole) to embark on a journey through the underworld, and the name Frisk is only revealed after a True Pacifist runs.

As evidenced by his perpetually blank expression and lack of dialogue, Frisk’s personality is a clean slate to accentuate in whichever direction the player chooses. Even though he speaks to NPCs, we don’t see or hear this dialogue.

Frisk and their choices have great importance over the fate of both the underworld and the surface. He is kind or evil based on how the player decided to play the game.


Undertale Characters sans

  • Creature type: Monster (Skeleton)
  • First appearance: Snowdin Forest
  • Skills and abilities: Teleportation and comedy
  • Role: Friend (Neutral Route and True Pacificist), Antagonist (Genocide)
  • HP: 1 (due to the player only needing to land one blow on the Genocide run)
  • Gender: Male

Sans has become one of the most recognizable characters in the game — and with good reason. A living skeleton donning a blue fleeced hoodie and a wide smile, he’s known for his very chill personality — a trait frequently referred to as laziness by his initially much more driven brother, Papyrus. We interact with Sans throughout the game more so than most other characters, and despite his seemingly carefree attitude, we learn that he is one of the most insightful and philosophical characters we converse with.

Perhaps his most memorable trait is his sense of humor. He’s constantly cracking ‘dad jokes’ showcasing many of Undertale’s more juvenile moments — putting whoopie cushions on the seats of other characters, for example.

While laid back is verging on understatement, he’s an uncommonly powerful combatant. The player will only experience his battle prowess during selected runs; during that experience, the player is also treated to the most recognizable piece of music in the game: Meglovania. Outside of his main interactions, he also appears at random points in the game — he can even be found selling hot dogs for 30 gold an order at a stall in Hotland, for example.


Undertale Characters papyrus

  • Creature type: Monster (Skeleton)
  • First appearance: Snowdin Forest
  • Skills and abilities: Physics glitching and cooking pasta
  • Role: Friend (Neutral Route and True Pacificist), Antagonist (Genocide)
  • HP: 680
  • Gender: Male

Compared to his brother, Papyrus is decidedly more intense in his persona. Flamboyant in his dialogue, his text boxes are present with erratic capital letters that give the impression he is constantly shouting or at least has a loud voice, and he’s obsessed with capturing a human to become a member of the Royal Guard.

While loyal to Undyne and the cause, his real motivation for joining this group is borne out of a longing for appreciation and friendship. He ultimately just wants people to like him and appear ‘cool’ — his apparent narcissistic bravado is actually a mask for his insecurity. Notably, he is the only character who doesn’t attempt to kill the player when fighting them; he won’t reduce their health beyond 1 HP.

Papyrus has a longing to be loved and is one of the more lonely characters we encounter. He would never want to display such a weakness, however. He’s almost always kitted out in an outfit he calls his ‘battle body’ consisting of a red hero’s cape, a gold chest plate, and red gloves and boots.

He also has a particular love of puzzles, forcing the player through many of them before their final encounter with him. Papyrus even has an affinity for cooking pasta (as terrible tasting as it may be).



  • Creature type: Monster (Fish)
  • First appearance: Waterfall
  • Role: Antagonist (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Enhanced strength & speed and high determination
  • HP: 1500
  • Gender: Female

Undyne is head of the Royal Guard. She is a fierce but fair leader who does everything she can to protect the monsters of the underworld and enact the will of her own leader, Asgore. Early in the game, she pursues the player clad in bulky metal armor and wielding bright blue magical spears. She vows to succeed in bringing Asgore an eighth human soul to break the barrier once and for all.

Her personality can be considered stern and guarded — a closed book wholly dedicated to one cause. Nevertheless, it is apparent throughout the story that she is deeply thoughtful and kind: her moral compass is absolute despite the hard exterior she displays.

Undyne is also unwaveringly selfless, as evidenced in her attempts to exchange her life for Monster Kid’s when he falls from a bridge. Notably, while there exist many self-proclaimed heroic and brave characters in the game, Undyne is one of the only ones who unconditionally embodies that sentiment.

Apperance-wise, she best resembles an anthropomorphic aquatic monster with fins and gills, but sports a ponytail and a distinctive eyepatch. She is also one of the most idolized characters in the game as both Dr. Alphy’s biggest crush and Monster Kids’ ultimate hero and role model.


alphys date undertalebut better
Image By Monica Phillips
  • Creature type: Monster (Reptile)
  • First appearance: Hotland lab
  • Skills and abilities: Scientific prowess
  • Role: Friend
  • Relationships: Lover to Undyne, creator of Mettaton, and Researcher for Asgore
  • Gender: Female

Reptilian in form, Alphys works and lives in the labs of western Hotland as Asgore’s royal scientist. Despite being highly intelligent, she suffers from incredibly low self-esteem and frequently puts herself down. As indicated by her dialogue boxes, she has somewhat of a stammer, too. She also frequently expresses her infatuation with Undyne and enjoys Anime and writing fan fiction.

Notably, she is the creator of another key character in Undertale: the robot Metaton. Alphys guides the player through Hotland, frequently thwarting Metaton’s violent and increasingly complex ways of killing Frisk, saving the protagonist’s life on multiple occasions.

While you may not realize it on your first playthrough, Alphys is a drastically important character regarding the game’s main events. She is directly involved in the creation of Flowley; her underground lab holds many secrets about the game’s lore and important interactions between characters.

On the side, she’s an avid social media poster. Throughout Frisk’s adventure through Hotland, we’re frequently interrupted by her continuous status updates as she discusses her interests in babbling detail.


Undertale Characters napstabloock

  • Creature type: Ghost
  • First appearance: Ruins
  • Role: Friend
  • Skills and abilities: Magic tears and making music
  • HP: 88
  • Gender: Ambiguous

While Napstablook is a relatively minor character, he’s nonetheless become a big hit with fans. A benevolent ghost, the player encounters him at various points during the story; they first find him pretending to be asleep within the ruins, blocking the player’s path. They later save the player from Mad Dummy’s attacks and subsequently invite them to their home.

The player also gets to explore his house, and it’s here that we discover Napstablook lives a life of relative solitude. His room is centered around a record player where Frisk can play several ghostly tunes, and we learn the character has a passion for online music sharing.

His personality is quite somber, with one of his attacks in battle literally being his falling tears. He lives alone accompanied only by his farm of snails — a business of which he is the sole employee.

Asriel Dreemurr

Undertale Characters asriel dreemurr

  • Creature type: Monster (Goat)
  • First appearance: New Home
  • Role: Contextual character (True-Pacifist), Antagonist (Genocide)
  • Skills and abilities: Control over existence (Genocide)
  • HP: Invincible (9999) as The God of Hyper Death (Genocide)
  • Gender: Male

Asriel’s tale as we know it begins when the first fallen human, Chara, falls into the underworld. Naturally kind and caring, he befriended the human and they became very close — so close, in fact, that his mother and father, Asgore and Toriel, adopted Chara as their own child.

This cosey family of four would not last, however. Having fatefully discovered the poisonous quality of Buttercup flowers, both Asriel and Chara hatched a plan in a bid to reach the surface and free everyone. Chara would poison herself with the flowers and Asriel would take her soul, enabling him to pass through the barrier. Once on the surface, he would collect the other six souls required to free the monsters of the underworld.

This didn’t go to plan. Chara died, and her last wish was to see the golden flowers she remembered from the surface once more. In a valiant attempt to fulfill this will, Asriel ventured to the surface but was immediately attacked by the humans. He sadly died from his wounds where he lay over a golden flower bed in New Home, his dust scattering amongst the beds where he lay.


Undertale Characters chara

  • Creature type: Human/Ghost
  • First appearance: Mt. Ebott
  • Role: Contextual character (Genocide)
  • Skills and abilities: Resurrection and healing
  • Relationships: Best friend of Asriel, ex-stepdaughter of Toriel and Asgore
  • Gender: Female

Chara is easily one of the most complex characters in the story, with her appearance mostly reserved for the genocide route or as a more ethereal being. In appearance, they are very similar to Frisk, with similar clothes and hairstyle and differing mostly in expression. Where Frisk retains a blank expression throughout the game, Chara’s eyes are fully open, her cheeks rosy red, and her mouth upturned into a smile.

They were the first of the seven humans to fall into the underworld, and represent the same soul color (red) as Frisk. Upon being found by Toriel and Asgore’s son, Asriel, Chara was taken in as part of the family. Chara was dissatisfied, however. She is considered to have hated humanity, and her journey to the top of the mount was a pilgrimage of escape.

While it’s not completely clear what happened, we do know that Chara enlisted Asriel in a plan to reach the surface to recover enough souls to break the barrier. It is believed that she poisoned herself to enable Asriel to utilize her soul.

Even once her soul was harvested, Chara didn’t exactly die and was instead channeled through Asriel as he reached the surface. When Asriel died, Chara too was buried where the player fell beneath the flower beds. By some mechanism, she was reborn when Frisk fell down to the underworld to that exact spot. She lives vicariously through him and the player throughout the game.

Interestingly, Chara isn’t always the name given to the first fallen human. The name the player inputs at the start of the game — often mistaken for the name of the protagonist — is the name given to the Chara character.


Undertale Characters mettaton

  • Creature type: Robot
  • First appearance: Hotland lab
  • Role: Antagonist (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Role play and entertaining
  • HP: 1600 as EX version and 30000 as NEO version
  • Gender: Male

Mettaton may be a robot, but he’s significantly different than you might expect. Created by Alphys, he was built as an entertainer who hosts his own successful and popular TV show (the only show in the underworld, in fact). Notably, he was created with a soul, emboldening his sentience and sense of purpose.

Mettaton functions primarily as an antagonist — one with a proclivity for brutally murdering humans, though he explains he only ever attacked Frisk to prevent Asgore from taking his soul, thus becoming a savior to further his own fame. He’s also been described as being incredibly demanding and difficult to work for.

Aside from his interactions with Frisk, Mattaton’s sole purpose is to put on a show and reap the rewards and adoration through ratings. He’s the number one celebrity of the underworld and presents as one of the more divisive and morally ambiguous characters in the game. In many ways, he doesn’t have a horse in the race and is only really interested in furthering his own selfish pursuits.

D. Gaster

Undertale Characters d gaster

  • Creature type: Monster (Unknown type)
  • First appearance: Art assets first seen in Waterfall
  • Role: Contextual character (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Science and engineering
  • Relationships: Possible father of Sans and Papyrus
  • Gender: Presumed male

D. Gaster is possibly the most elusive character in the game, and most certainly someone who has stirred the most intense rumors within Undertale’s online community. He is described as being Asgore’s Royal Scientist before Dr. Alphys was. During his position in the labs, he created the CORE: a large, expansive structure that is the source of the magical electricity source that powers the underground.

Most of what we know about the character in the game is revealed through a selection of secret NPCs known as Gaster’s Followers. Not only do they reveal the above information, but they also divulge mystical snippets about his untimely disappearance. It is unclear whether he fell to a problem with his own creation, perished due to an experiment gone wrong, or simply vanished from existence due to some other perplexing magical force.

Adding to the elusiveness of this character, his appearance is unknown. Several unused assets can be discovered, and it has become accepted that some of these may represent Gaster’s form. The River Person is also said to have eluded to him through his riddled way of speaking, and the theories about W.D. Gaster become more numerous each year — especially since the release of Deltarune.


Toriel Alphys Undertale

  • Creature type: Monster (Goat)
  • First appearance: Ruins
  • Role: Friend (Neutral and True-Pacificist), Antagonist (Genocide)
  • Skills and abilities: Elemental summoning and nurturing
  • HP: 440
  • Gender: Female

Toriel is unquestionably kind, acting as a mother figure not only to the protagonist but to the underworld as a whole. While clearly wise and intelligent, she also has a fun side, frequently cracking jokes devised from a journal that can be found in her bedroom.

She also enjoys baking, and her house is depicted as warm, cozy, and inviting — a contrast to the otherworldly environmental variety in the majority of the game.

Her past is one of great loss. Before the events of Undertale, she was married to Asgore with whom she had a son, and the two also adopted the first child to fall into the Underground (Chara). Following the tragic deaths of both of these individuals, Toriel ultimately left Asgore in disgust having learned of his plans to harvest human souls and instead sought a new home in the Ruins.

She is also shown to have a friendly relationship with Sans; he explained how he once happened upon Toriel’s house, and the two developed a friendly relationship born out of a shared affinity for knock-knock jokes. During their friendship, she had Sans promise to protect any human that passes through.

Protecting fallen humans is seemingly her primary objective. It is thought that she tended to the needs of the other six children who fell to the underworld, representing a juxtaposition to the goals of her ex-husband.


Undertale Characters muffet

  • Creature type: Monster (Spider)
  • First appearance: Hotland
  • Role: Antagonist (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Commandeering the spiders, baking, and making tea
  • HP: 1250
  • Gender: Female

The player meets Muffet during their journey through Hotland. She leads the spiders of the underworld and runs an extortionately priced bake sale. Her appearance is odd, having a pot of tea and a teacup in two of her hands that she seemingly uses against the player during their fight with her.

Her personality is considered quite menacing; she has a somewhat polite way of speaking but her dialogue describes various macabre fates that will supposedly befall the player should she win the fight between them. Alongside her arachnid allies, she also has a ‘pet’ monster that attacks the player during various points in battle — the monster is what appears to be an oversized muffin with serrated teeth.

Despite her thirst for the spoils of battle, she is easily dissuaded once she realizes Frisk’s plan was no risk to spider-kind. The player’s battle with her is cut short when a telegram is delivered to her by a spider minion explaining the player’s intentions.


Undertale Characters flowey

  • Creature type: Sentient plant
  • First appearance: Ruins
  • Role: Antagonist (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Powers to reset time
  • HP: Invincible (9999) as Photoshop Flowey
  • Gender: Spiritually male

Flowey is the first character Frisk interacts with once they fall down into the underworld. Luling the player into a false sense of security with their initially cute appearance and welcoming dialogue, we soon learn Flowey is as malevolent as they come. Flowey was once Asriel, but the essence of the once earnest and kind young child is long gone.

Several years after Asriel’s death, Dr. Alphs discovered a substance that would come to be named Determination: an ethereal compound that enabled the retention of power within a soul even after the individual had died. Alphys harness this new energy, and following several unsuccessful attempts to make monster souls more powerful, she tried injecting it into a soulless object: a flower.

One of the flowers that were injected came from the same bed of golden plants where Asriel breathed his last breath. Somehow, the flower was reborn — without Asriels soul, but with his memories and some of his essence. He was reborn with a newfound hatred for monster kind, and he discovered a new-found ability to reset time itself.

This aspect initially confused players, as Flowey would break the fourth wall several times, corrupting and manipulating physical save files on the player’s system toward the end of the game.

Asgore Dreemurr

Asgore Undertale

  • Creature type: Monster (Goat)
  • First appearance: New Home
  • Role: Antagonist (Neutral, True-Pacificist, and Genocide)
  • Skills and abilities: Elemental summoning and brute strength
  • HP: 3500
  • Gender: Male

Asgore Dreemurr is the king of the land described as the underworld. Despite his surprisingly kind demeanor, he still represents one of the main antagonists in the game. Having lost his son due to the underworld’s involvement with humans, the king’s ultimate goal is to harvest a total of seven human souls to break the barrier enclosing the Underworld and all its inhabitants from the surface.

Asriel portrays somewhat of a juxtaposing personality. On the surface, he appears upbeat: a jolly character with a love for gardening. Despite his towering stature and decorated appearance, he is notably kind. On the other end of the spectrum, the king is a deeply sad individual, broken by the loss of his family as well as his wish not to have to kill anyone. He does what he does out of duty to his people, but hates the fact that he has to. All monsters in the Underworld look to him as their bastion of hope.

Other Noteworthy Side Characters

Undertale is full of cool characters besides those detailed above, so this section will provide a brief overview of some of the more minor encounters.

Monster Kid: Monster Kid is a young monster desperate to gaze upon his idol, Undyne. Clumsy but full of energy, the character follows Firsk for part of his journey, unaware that they are indeed the human Undyne is perusing. They’re also part of a key moral choice the player faces.

Mad Dummy: Mad dummy is an angry and erratic ghost character encountered in the Garbage Dump. They take the form of a combat dummy and are a key marker of the player’s moral decisions, reacting differently depending on how the player treated their interaction with the inanimate dummy from the ruins. Irrespective of how they approach the player, Frisk must battle them to proceed.

Annoying Dog: The Annoying Dog is a side character who appears at several intervals in the game, and usually sabotages something relating to either the player or one of the other characters they’re talking to. The dog can also be placed in the player’s inventory, which causes many problematic scenarios. The character is considered to represent Undertale’s creator, Toby Fox; in videos for the Kickstarter and in Interviews, Fox often portrays himself as the Annoying Dog.

River person: River person acts as a fast-travel service for the player. Cloaked in a hooded purple robe that does not reveal their face, the character provides travel on their boat to Waterfall, Snowdin, and Hotland — though this isn’t all they offer. River Person also provides context and hints to the player during the ride, adding yet another layer of theory, speculation, and intrigue to the game’s lore and plot.

Undertale Characters river person

Frequently Asked Questions

Question: I’ve seen that Toby Fox made another game called Deltarune. Is this game a sequel to Undertale?

Answer: Toby Fox has gone on record to state that Deltarune is not a sequel to Undertale — whether he’s telling the truth here, however, is a different matter. Deltarune is set in a different in-game universe and a separate timeline from Undertale, but uses many of the same characters.

One of the best deep dives I’ve come across on the topic was this video by LiNX 4 — but make sure you’ve finished both games before checking it out!

Question: Is Chara evil?

Answer: This topic has been debated for many years, and the answer still isn’t clear. While we can’t definitively call her evil, she’s certainly one of the more morally grey characters in the game. Given that Asriel himself considered her to be “not the greatest person” upon reflection, and also that he was clearly manipulated by her in a way that lead to his death, we can at least confirm she was not wholly good.

Question: What is the Chara-Frisk-Player triangle?

Answer: You’ll likely have heard this term banded around a lot when researching Undertales characters. The Chara-Frisk-Player triangle refers to the clever but complicated relationship between those three entities. Once you’ve experienced all three endings, you’ll have a lot to think about: Is the game breaking the fourth wall? Is Chara possessing Frisk? Is Chara present in every run? Is the player controlling both Chara and Frisk?

Also named the Chara-Frisk-Player Trifecta, the topic is one of the deepest Undertale rabbit holes you can explore.




I hope you enjoyed this rundown of Undertale’s excellent cast of unique characters. I highly recommend checking out the Undertale board on Reddit for more information on the lore behind each character. Have fun!

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