Characters of Undertale and Deltarune

A screenshot from the "True Pacifist" route's ending of Undertale, featuring friends the player makes along the way. From left to right: Toriel, Sans, Papyrus, Frisk, Undyne, Alphys, and Asgore.

A screenshot of a scene from either the "Pacifist" or the "Neutral" route of Deltarune Chapter 2. From left to right: Susie, Kris, Ralsei, Berdly, Queen, and Noelle.

The fantasy role-playing video game Undertale, developed by Toby Fox, takes place in a universe where monsters once coexisted with humans, but have long since been forgotten in modern times. Its main character is a human child who falls into the Underground, a large cave below Mount Ebott where human wizards trapped the monsters following an ancient war and from which they seek to escape. Its spiritual successor, Deltarune, is an anagram of Undertale, and takes place in a parallel universe featuring many of the same characters. In Deltarune's universe, humans and monsters still coexist in the modern day. The main character, Kris, discovers the Dark World, an alternate realm inhabited by Darkners, which are beings brought to life from objects originally from the Light World (the regular world). They embark on a quest to close the Dark Fountains before darkness overtakes the real world.

The following is a list of major characters who appear in one or both games in the series. The characters of both games were well received by critics and fans for their humor and in-depth characterization shown through different moral choices. Some characters gained notoriety for their ability to break the fourth wall, manipulating gameplay elements normally only accessible to the player, such as saving.

Undertale and Deltarune

Toriel and Asgore Dreemurr

Main articles: Toriel and Asgore

Toriel is among the first characters met by the human, a powerful goat-like woman (namely Boss Monster) living in the Ruins. She is the former queen of the Underground, where monsters live, having been married to its king, Asgore. She had a child with him named Asriel, who was killed by humans when he attempted to retrieve human souls to break the barrier, as part of Chara's plan. This led Asgore to slowly collect human souls himself to free the monsters from the Underground, causing Toriel to leave. She takes the protagonist in after they fall into the Underground. She attempts to keep them from leaving due to the worry that her ex-husband, Asgore, would hurt them, but allows them to leave in the end. The protagonist progressively goes through the Underground to confront Asgore, where he forces him to fight them.

In Deltarune, its main protagonist, Kris, lives with their adoptive mother Toriel, a teacher, while Asgore lives apart from them and lives at his flower shop.

As Boss Monsters, once Toriel and Asgore have children, they only grow when their child reaches their age, and cease to grow if the child disappears or dies.

Asriel Dreemurr

Main article: Flowey

In Undertale, Asriel is the now-deceased prince of the Underground, whom Chara, his adoptive human sibling, convinced to participate in a plot to collect six human souls from the surface. After absorbing Chara's soul and leaving the Underground, Asriel refused to fight back against the humans who mistook him for Chara's killer and was killed by them. Asriel was then reincarnated as Flowey, but without his empathy and compassion. In the game's "True Pacifist" route, Flowey transforms into an adult representation of Asriel, known as the "God of Hyperdeath", serving as the final boss of the route. After being defeated, Flowey returns to the form of child Asriel and regains his empathy, albeit only temporarily.

Jason Schreier of Kotaku called Asriel's final boss fight one of the greatest in video game history, citing its climactic music and the necessity to save your friends from him. Describing the sequence as "spectacular" and noting the emotion of the fight, he stated that, "if you’re not already bawling as you mash the SAVE button over and over again during the final part of this fight, well... you will".

In Deltarune, Asriel is Kris's brother, but has left for college and has not yet made an appearance in the game.

Sans and Papyrus

Main articles: Sans (Undertale) and Papyrus (Undertale)

A pair of skeleton brothers known for their outlandish human-capturing schemes, Sans and Papyrus function as comic relief within Undertale. They are respectively named after the typefaces Comic Sans and Papyrus, which they use in their dialogue, with Papyrus speaking in all-uppercase, and Sans mostly speaking in all-lowercase.

Papyrus is egotistical yet incompetent, but is "pretty freaking tough", according to Undyne. Papyrus loves puzzles and pasta, and wishes to join the Royal Guard. Despite this, he is shown to be a kindhearted and genial character who believes that anyone can be good if they try.

Sans is a clever, laid-back slacker and trickster. He often pulls practical jokes and makes puns, and bonds with Toriel over their shared love of the latter. Sans also frequently breaks the fourth wall. In Undertale's "Genocide" route, Sans acts as the game's final boss, where he reveals some control over the game's mechanics, and uses them against the player.

In Deltarune, Sans runs a grocery store known as 'Sans, additionally working as its cashier, and Papyrus is not seen.

Undyne

Main article: Undyne

In Undertale, Undyne is the powerful leader of Asgore's Royal Guard. She is a humanoid with fish-like features. While initially presented as intimidating, her clumsy behavior in combat is heavily inspired by anime, which she believes to be an accurate representation of the human world. She possesses a small amount of Determination: a substance that makes humans far stronger than monsters and enables her to persist upon death. It has been theorized this is due to the intervention of her love interest, Alphys, who was conducting experiments on injecting Determination into vessels, such as monsters and flowers, which led to Flowey's creation. Compared to Asgore, who harbors remorse for killing others, Undyne holds a deep hatred for humans and will not hesitate to kill them, although this lessens if the protagonist befriends her.

In Deltarune, she became the town's police chief after Asgore was fired. She notably lacks an eyepatch over her right eye and only knows Alphys in passing. In Chapter 3, Undyne enters the Dark World of the Dreemurr household just in time to rescue the party from the Roaring Knight. However, she is quickly snatched away by the Knight and brought to the shelter south of Hometown.

Alphys

Main article: Alphys

In Undertale, Alphys is Asgore's Royal Scientist and Undyne's love interest. She is a shy, nerdy, lizard-like monster with low self-esteem, and is a heavy otaku. She created Mettaton's robot body in order to make Asgore think she was capable of creating artificial souls to gain the position of Royal Scientist. She tries to earn the protagonist's trust by helping them "fight" off a malfunctioning Mettaton throughout Hotland, but he later reveals he was acting to make Alphys look better. She is the successor to W. D. Gaster, who served as Royal Scientist until he mysteriously disappeared.

The "True Pacifist" route reveals that she experimented with Determination on comatose monsters, but this caused them to fuse into creatures known as "Amalgamates". She keeps them locked away in the "True Lab".

In Deltarune, she is a teacher at Kris's school and is nervous around Susie.

Gerson Boom

In Undertale, Gerson is a shopkeeper in Waterfall. He explains that he was once a war hero known as the "Hammer of Justice" in the war against humans, but has since retired. He also mentored Undyne to an extent.

In Deltarune, Gerson is an author and historian who had died before the start of the game. However, he appears in the Dark World as the personification of a memento dedicated to him. Throughout Chapter 4, Gerson teaches Susie how to improve her healing abilities and serves as the chapter's superboss, adopting his "Hammer of Justice" persona to train Susie. He also helps the party defeat a Titan at the end of the chapter.

Exclusive to Undertale

Frisk

Frisk is a child from the Surface and the main playable character of Undertale, who searches for a means to escape the Underground after falling into it. They are not nameable by the player—in an act of misdirection, the player is asked to name the "fallen human" without specifying whether it is the protagonist. In the "True Pacifist" route, it is revealed that the "fallen human" superficially resembled Frisk, but had arrived years earlier. Frisk has an androgynous appearance and is a silent protagonist, keeping their true origin and nature ambiguous.

Chara

Chara, or the "fallen child", is a child from the human world, whom Toriel and Asgore took in prior to the game's events. Although the player can name them, Chara is referred to as their "true name" on the naming screen. It is stated that they climbed Mount Ebott for an "unhappy" reason and that they hated humanity. Chara told their foster brother, Asriel, of a plan to collect six human souls by killing themself, letting him absorb their soul and leave the Underground as one being. The control was split between the two, with Chara making the decision to bring their empty human body with them. Upon reaching Chara's village, the humans thought Asriel killed them and attacked. Asriel resisted Chara's intent to use their "full power" against the humans, leading to their deaths and Chara's burial in the Ruins. In the game's "Genocide" route, Chara is resurrected as a soulless and demonic being who seeks to erase the world, referring to themselves as "the demon that comes when people call its name".

Flowey

Main article: Flowey

Flowey is a flower who initially pretends to be kind-hearted, but is truthfully a sadistic sociopath who adheres to a "kill or be killed" philosophy. He once had the ability to operate outside the laws of the universe via saving and loading save files, like the player character. A powerful, eldritch version of him known as "Photoshop Flowey" or "Omega Flowey" serves as the final boss of the game's "Neutral" route. If he is spared after his fight as Photoshop Flowey, he says he cannot understand the player character's kindness towards him despite his threat to murder their loved ones, and gives tips to the player on how to get a better outcome. He is later revealed to be the reincarnation of Asriel Dreemurr, the deceased prince of the Underground. Flowey, like Undyne, possesses Determination, as Alphys injected it into one of Asgore's first golden flowers during her experiments.

Mettaton

In Undertale, Mettaton is a robotic entertainer who is the Underground's sole celebrity, hosting various television shows and having products, brands, and a hotel in Hotland themed after him. He is an egotistical glory-seeker and wishes to take a human soul to travel to the surface and become a celebrity among the humans, and tricks Alphys into helping the protagonist reach the CORE so he can kill them under the pretenses of making her look like a hero. It is revealed through diaries in an abandoned house that Mettaton was originally a ghost who dreamed of creating a perfect body for themselves. They achieved this when they befriended Alphys and she created his body (in order to make Asgore think he was an artificial soul), but at the cost of abandoning their cousin Napstablook. In the "Genocide" route, Mettaton transforms into a seemingly powerful form called Mettaton NEO, but the player kills him in one hit. In the "True Pacifist" route, he reunites with Napstablook, who becomes his sound mixer.

W. D. Gaster

Main article: W. D. Gaster

W. D. Gaster, often referred to as "Doctor Gaster" or simply "Gaster", was the former Royal Scientist and created the CORE, the Underground's power system. Following his abrupt and mysterious disappearance, Alphys took up his position. Gaster's presence in the game is hidden, only being directly mentioned in rare Easter eggs and internal game data discoverable through data mining. Despite his near-complete absence from the game, the mystery surrounding the nature of his presence has caused him to gain a sizable fan following.

In Deltarune, while he has not yet been seen, various hints imply he is tied to the game's overarching story.

Exclusive to Deltarune

Kris Dreemurr

Main article: Kris (Deltarune)

Kris is an androgynous, introverted teenage human whom the Dreemurr family adopted and the main character of the game. They are stated to have a trickster personality, and others generally perceive them as somewhat troubled.

While Kris is the player character, there is a separation between Kris as a character and the player as a separate entity that controls Kris's body. Kris is normally controlled through a soul that uses the player's inputs, though the player's control can jump to other characters if necessary. Other characters often note the absence of Kris's usual personality during the player's influence, and it is implied throughout the game that Kris harbors their own thoughts and feelings outside of the player, and can outright contradict some of their choices.

Kris is able to temporarily remove their soul from their body and exercise free will outside of the player's control. For example, during the ending sequence of Chapter 1, Kris throws the soul into a birdcage, at which point the player's movement inputs control the trapped soul, not Kris.

Susie

Susie is a purple, dragon-like student who is strong and has a gruff, tomboyish appearance and demeanor. She is one of the player's main party members and wields an axe. She starts out aggressive and unwilling to use mercy or befriend people, but mellows out over the course of Chapter 1 and becomes more friendly and boisterous in Chapter 2. She befriends Lancer, Ralsei and Kris, becoming particularly close with the latter, over the course of Chapter 1.

Noelle Holiday

Noelle Holiday is a timid fellow student resembling an anthropomorphic reindeer, who is a childhood friend and classmate of Kris and has a crush on Susie. She joins the player's party in Chapter 2. In the Dark World, she wears a white robe and is proficient in magic. Her "IceShock" spell can be used to freeze enemies solid, and, in the "Weird" route, she traps Berdly in ice with her "SnowGrave" spell. She has an older sister nicknamed Dess, who is implied to be missing or dead. She joins the party again in the Light World segment of Chapter 4, where she shows Kris and Susie her house.

Carol Holiday

Carol Holiday is Noelle's mother and is the mayor of Hometown, who first appears in Chapter 4. After seeing Susie hold Dess's guitar, she takes it out of her hands and angrily demands her to leave.

Berdly

Berdly is a know-it-all student resembling an anthropomorphic bluebird who starts off snobbish and as Kris's rival in Chapter 2, where he works with Queen, and fights the party three times. However, he later becomes their ally. Prior to becoming allies with Kris, he started off with a snobbish and nerdy persona, looking for praise for his perceived intellect. Should the player manipulate Noelle to freeze Berdly in the "Weird" route, he appears to be unresponsive, and is later found in a coma in Chapter 4.

Ralsei

Ralsei (/ˈrɔːlseɪ/; RAWL-say) is the prince of the Dark World, who wears a green robe and wizard-like hat that conceals him in shadow in Chapter 1. Ralsei is introduced in the Dark World as a young prince who has been waiting for the Lightner heroes to arrive and fulfill a prophecy, which he explains, though not completely accurately. He explains to Kris and Susie that they must travel together to seal the Dark Fountains and save the light and dark worlds from falling into chaos. He is known for his gentle demeanor and compassionate personality. Reviewers describe him as an “adorable” character with a kind-hearted nature. When his hat is removed at the end of Chapter 1, he is revealed to resemble Asriel, in addition to their names being anagrams.

Lancer

Lancer is a miniboss in Chapter 1, a personified Jack of Spades card who befriends the protagonists and becomes a recurring character. He is the son of King, the final boss of Chapter 1. He is energetic yet incompetent in his attempts to stop the heroes to earn his father's respect. His gradually-developing friendship with Susie is what causes him to rebel against his father and assist the protagonists. In Chapter 2, he helps Kris escape captivity, while in Chapter 3, he helps the party during Tenna's "boards," and helps them defeat Rouxls Kaard.

Jevil

Jevil is a personified Joker card who appears in Chapter 1. He was the former court jester and partner of the former magician and now shopkeeper, Seam, but was locked away after an interaction with an unknown figure drove him to madness. He began to see his whole world as merely a game and all its inhabitants as parts of it, influencing Seam to adopt a similarly nihilistic outlook on life. Despite being locked in a cell, he now believes all the other inhabitants of the Dark World have imprisoned themselves and he is the only free Darkner remaining. Upon being set free, he challenges the party to a battle as a "game" and serves as the superboss of Chapter 1.

King

King is the final boss of Chapter 1, a personified King of Spades card and Lancer's father. Originally one of four kings who ruled over the Card Kingdom, he was put in power when the Knight came to their Dark World and overthrew them. He is shown to be a tyrannical figure with little care for his subjects or family, zealously dedicated to the Knight, and plans to take over the Light World as retribution for the Lightners abandoning him. He is jailed at the beginning of Chapter 2, where he remains during Chapters 3 and 4.

Queen

Queen, real name "Serial Number Q5U4EX7YY2E9N", is the main antagonist of Chapter 2. She is a personified laptop who attempts to capture the party multiple times, although she is mostly friendly, eccentric, and does not understand the threat the Dark Fountains pose until Ralsei explains it to her, causing her to stop her plans. While she partners with Berdly to capture the party, she dislikes him, to the point of routinely forgetting his name. She possesses a gigantic robot called GIGA Queen, which acts as the final boss of the chapter, and is fought in a similar gameplay style to the Punch-Out!! series.

Spamton G. Spamton

Spamton G. Spamton is a personified spambot who resembles a marionette. He speaks in mangled, cryptic English peppered with bracketed marketing keywords like that of a spam email. Spamton has the personality of a used car salesman, and is obsessed with becoming a "BIG SHOT". He often states that he and Kris are alike in some way and that he is trapped as well, but usually projects his own flaws onto them.

After his appearance as a miniboss in the middle of Chapter 2, he functions as a shopkeeper, selling dysfunctional items for rapidly fluctuating prices, and then as the chapter's superboss, where he is known as Spamton NEO, after merging with a defunct robotic body. Before the game's events, he was a normal salesman who rose to success after communicating with an anonymous voice on his phone, but lost his job, home, and sanity when the voice abandoned him. In the Chapter's "Weird" route, he sells the ThornRing, and acts as the chapter's final boss, using his NEO form. Spamton is mentioned numerous times in Chapter 3, due to his connection to Tenna, who he formerly worked with, though his only physical appearance in the chapter is in a short Easter egg scene.

Mr. "Ant" Tenna

Mr. "Ant" Tenna is the main antagonist of Chapter 3. He is a personification of the Dreemurr family's unused television, operating as a game show host. His speech contains images in the place of certain text. He takes the main cast through 8-bit-styled "boards" and engages Kris, Susie and Ralsei in various minigames with an enthusiastic attitude, but is shown to be lonely as a result of being abandoned by his owners. When the main cast finds Toriel imprisoned in a gachapon ball, Tenna attempts to trap the cast as well, but they escape. After the protagonists defeat him at the climax of the Chapter, Tenna agrees to release Toriel. After the main cast offers to donate Tenna to a new owner, he is suddenly broken by The Roaring Knight. Depending on the player's actions, he can be fixed or remain broken.

The Roaring Knight

The Roaring Knight is the main antagonist of Deltarune. They have a slim, angular body, with antler-like horns and a helm resembling a frog-mouth helm. Their influence is teased by various characters throughout Chapters 1 and 2. The Knight makes their first appearance at the end of Chapter 3, where they destroy Tenna and battle the main party. While the party can optionally "defeat" the Knight and obtain a Shadow Crystal, they are downed in a cutscene afterwards, regardless. The party is then saved by Officer Undyne, who is kidnapped by the Knight and taken to the shelter south of town.

The Knight appears again in Chapter 4, as the chapter's antagonist. They fend off an attack by Kris and Susie at the start of the Dark Sanctuary, and at the end of the chapter, they create another Dark Fountain in the Dark World, spawning a Titan, which the party defeats.

Reception

Griffin McElroy of Polygon described Undertale's characters in general as not just funny, but "incredibly vulnerable", stating that he felt "real affection" for all of them after getting to know them. He called the game his most memorable gaming experience of the year due to his moral compass being guided by this connection. Noting that the characters were "well-written and relatable", he remarked that, when doing the Genocide run out of a desire to see all the game's content, he felt "genuinely terrible".

Richard Cobbett of Eurogamer stated that Undertale's characters were "layered" by RPG standards, calling them "not exactly Walter White in terms of complexity", but more deep than they initially seemed. Using the example of Sans, a "surprisingly complex figure", he noted that "most of the main characters are living with at least one unfortunate past decision or regret". He called the responsiveness of the world and characters an important part of Undertale's success, stating that "spending more time with familiar faces makes them feel real". In a separate review in PC Gamer, he called the game's characters "adorable", saying he had not laughed so hard in years.

Axel Bosso of Bloody Disgusting stated that the game's characters were difficult to trust, causing an anxious feeling with every encounter, starting with Flowey's switch from seemingly harmless to evil. Noting that "even the most inconsequential NPCs have an existential crisis and/or nihilism vibes around them", he said that it was "hard [...] to feel safe in this treacherous environment", though nevertheless remarking that "they became some of my most loved cast in quite some time".

Brendan Graeber of IGN positively highlighted the relationship between Kris and Susie in Deltarune, calling them "a dumbass duo with joint custody of a brain cell". He also highlighted the latter's character development throughout the game.