Monster Kid
You aren't gonna tell my parents about this, are you?
Monster Kid as Undyne drags them away
Monster Kid (JP: モンスターの子) is a young monster and major character in Waterfall who stops at nothing to see their idol, Undyne, in action.
Yo! You're a kid too, right?
I can tell 'cause you're wearing a striped shirt.Talking to Monster Kid in Snowdin
Monster Kid is a yellow monster with no arms, a tail, and spikes on the back of their head. Having no arms and frequently running everywhere, they trip and fall often. They have bags under their eyes. One of the bags are bigger than the other. They wear a yellow shirt with brown stripes.
Monster Kid looks up to Undyne as a role model. They are an innocent monster who assumes an energetic attitude that pervades most of their actions. They seem to be a bit naive, as well as a bit clumsy, as they trip frequently. They also use words like "c' mon", "dude", and "yo" frequently, usually considered childlike ways of interaction.
Despite the protagonist visibly frightening Monster Kid during the Genocide Route (once they discover the protagonist's intentions), they stand up to the protagonist with an intense expression, ready to protect the underground, trying to act like Undyne. Choosing to spare them aborts the Genocide Route, and Monster Kid's opinion of the protagonist returns to a more favorable state, showing a rather forgiving nature.
Monster Kid first meets the protagonist in Snowdin. They note how both of them are wearing striped shirts, so they both must be children. However, they do not seem to notice that the protagonist is a human child.
They later sneak out of Snowdin to explore Waterfall, looking for Undyne. They follow the protagonist, not knowing that the latter is a human whom Undyne is searching for, and they feel a little jealous of the attention that the protagonist receives from her.
While walking across a bridge, Monster Kid finds out that the protagonist is a human and reluctantly considers the protagonist an enemy. They try to say something mean to the human, in an attempt to become enemies, but feel bad for it and start to leave.
Just as Monster Kid leaves, they trip over the edge of the bridge and hang from it (presumably with their teeth) as Undyne approaches. The protagonist must make a choice:
- Help them climb back up: Monster Kid defends the protagonist from Undyne, who backs off. They decide to remain friends with the protagonist and leave for home.
- Let them fall: Undyne dives down after Monster Kid to save them. She is badly hurt but refuses to rest. They then tell Undyne that she was right about the human, who just stood there waiting for them to fall. This response makes Monster Kid hate the protagonist.
- Run to Undyne: Undyne saves Monster Kid and is badly hurt. They tell Undyne that she was right about the human, who was too eager to fight her to bother saving them. This response also makes Monster Kid hate the protagonist.
- Run away from Undyne: Undyne helps Monster Kid up, who tells her that the protagonist was just going to get help from others.
Monster Kid is seen cheering the protagonist on to victory in the bottom-right corner of the battle screen as they face off against Flowey. In the epilogue, they can be found in Snowdin. If saved earlier, they say they do not think Undyne is that great anymore, and that they found themself a new idol, implied to be Papyrus.[3] If not saved by the protagonist, however, they are still mad at them for not saving them.[4] They are also seen during the credits, attending Toriel's school.
Despite being warned by Undyne that the protagonist has hurt a lot of people, Monster Kid approaches the protagonist in disbelief. The protagonist turns away, and as Monster Kid questions the protagonist about not answering them, the protagonist silently approaches them with a "weird expression", causing them to step back.
Monster Kid begins to panic and wonders what they should do, and then stands up to the protagonist out of desperation, trying to act like Undyne, stating nervously that if the protagonist wants to continue to hurt others, the protagonist would have to go through them.
The protagonist then proactively engages battle with them, with the narration simply declaring "In my way." A slowed-down version of Anticipation plays during the battle. If the game is restarted after this cutscene, or when the protagonist dies, the scene is abbreviated: after Monster Kid approaches the protagonist, they trick Monster Kid into turning the other way, then engage the battle.
- If the protagonist attacks Monster Kid, Undyne takes the fatal blow in their place. The kid escapes while harboring a shocked expression, and the protagonist fights Undyne the Undying. Monster Kid is not seen again for the rest of the game; it is assumed they evacuated with the others.
- If the protagonist spares Monster Kid, they exclaim the protagonist was not as bad as they thought. This action aborts the Genocide Route, and the protagonist fights Undyne later in Waterfall normally.
- Genocide
- Yo!
- Yo.
- Undyne told me to stay away from you.
- She said you... You hurt a lot of people.
- ...
- But, yo, that's not true, right!?
- ...
- ... yo... Why won't you answer me?
- A... a... and what's with that weird expression...?
- Oh... Oh man...
- (Man, my h-heart's pounding right out of my chest...)
- (... what would Undyne do?)
- (...)
- Yo...
- Y-you'd b-better st-stop r-right where you are...
- Cause if you w-wanna hurt anyone else... you're...
- You're gonna have to get through me, first.
- A... and... and...
- [Post-introduction, subsequent resets]
- Yo!
- Yo, dude... I... I heard some things, and...
- What? Look over here? What for
- Genocide
- ... [Neutral]
- [Attack]
- Undyne... You're... You're hurt...
- [Undyne] Hurt? It's nothing.
- [Undyne] Next time, listen when I tell you to leave, okay?
- Undyne... I...
- [Undyne] I'll take care of this!
- [Undyne] Get out of here!
- Genocide (aborted)
- S-see? I knew y-you weren't so bad!
- I've gotta go tell Undyne she was wrong about you!
- Looks like free EXP. [Check]
- In my way. [Encounter]
- Monster Kid quivers anxiously. [Neutral]
Monster Kid was designed by Magnolia Porter, creator of "Monster Pulse". She also designed Snowdrake, Ice Cap, Jerry, and helped design Gyftrot. The Pokémon Scraggy might be the inspiration for Monster Kid's design; both are small, yellow, bipedal lizard-like creatures with protruding teeth. While Scraggy may have arms, it has to use them perpetually to hold up its pelt, which is a lot like not having arms at all, just like Monster Kid.
Monster Kid was referred to with "he/him" pronouns in initial printings of the UNDERTALE Art Book.[5] Later printings removed these references.[6] In the Japanese translation, Monster Kid uses the masculine pronoun オレ (ore) for themself, which is usually only used by males when speaking casually to friends.[7] In Legends of Localization Book 3: UNDERTALE, an officially licensed book on the Undertale Japanese translation written in consultation with Toby Fox, confirms that Monster Kid has no specified gender.[8][9]
In Deltarune, Monster Kid appears as a minor character and one of Kris's classmates in Hometown's school. Like their Undertale counterpart, Monster Kid is shown to be friendly towards others with the exception of Susie, and is academic partners with Snowy.
Monster Kid's tarot card as Major Arcana XIX, "The Sun".
Monster Kid as seen behind Undyne the Undying on her tarot card.
Monster Kid plush sold on Fangamer
Artwork from Undertale's 5th anniversary.
- Monster Kid's assumption that the protagonist is a kid because of their striped shirt may be a reference to the Mother series, where the main protagonists of each game are kids who wear striped shirts.
- Monster Kid's line after the protagonist allows them to fall from the ledge mentioning they were "almost a goner" may be a reference to Goner Kid.
- In a scrapped idea for an arcade in Hotland, Monster Kid would have made various comments while the protagonist played games. This concept later served as the basis for the gameplay of The Legend of Tenna in Deltarune.[10]
- Goner Kid
- Monster Kid article on the Deltarune Wiki
- ↑
That sure was a tense scenario. I just wanted to help that poor kid, but... I thought if I tried, you'd attack me! Thankfully, you ended up saving them.
— Undyne - ↑ UNDERTALE 10th Anniversary Stream - Day 1 (04:07:01) on YouTube
- ↑
Maybe Undyne... Isn't actually as cool as we thought.
— Monster Kid
She's just kinda... mean.
But YO!!! I just found out about someone WAYYY cooler!!!
Nyeh heh heh!!! - ↑
Yo... There you are!
— Monster Kid
I've been kinda worried about you since you ran away.
... but now I'm just kinda mad, ha ha.
If Undyne hadn't saved me, that woulda been bad... - ↑
Temmie’s first sprite of monster kid. He looked really pissed off so I changed his face.
— Toby Fox, UNDERTALE Art Book, pg. 169 - ↑
Temmie’s first sprite of monster kid. Looked too angry, so I changed the face.
— Toby Fox, UNDERTALE Art Book, pg. 169 - ↑
Monster Kid (who talks like a punk kid) and Mad Dummy use ore.
— zarla-s on Tumblr, August 22, 2017. - ↑ "Although Monster Kid uses the masculine pronoun オレ (ore) in Japanese, Toby designed the character to have no clear gender" — Clyde Mandelin, Legends of Localization Book 3: UNDERTALE, pg. 159
- ↑ "In the English script, a character called “Monster Kid” speaks like an energetic youth who loves to use slang. The translator preserved these attributes in Japanese, but this led to a problem: Monster Kid’s gender is never specified in the original script, yet this Japanese speaking style makes the character sound like a teenage boy. After consulting with Toby, the translator gave Monster Kid the assertive, masculine pronoun ore." — Clyde Mandelin, Legends of Localization Book 3: UNDERTALE, pg. 159
- ↑ 前からずっと、「友だちといっしょにゲームをしているあの感じを、ゲームの中で再現したい」と思っていました。みんな口々に冗談を言ったり、画面の中で起きたことにちゃちゃを入れたり、みんなに見せたいがために、わざとバカなことをしたり…。そういうのを、ずっと前からやりたくて。
本当は『UNDERTALE』で、「ホットランド」にゲームセンターを作りたかったんです。モンスターの子といっしょにゲームができて、プレイヤーがゲームをしているあいだ、モンスターの子がいろいろコメントする、っていう…。「THE LEGEND OF TENNA」のシーンで、本当に友だちとゲームをしているように感じてもらえたら、うれしいです。 ("For a long time now, I've been thinking, "I want to recreate that feeling of playing games with friends, right inside the game itself." Everyone cracking jokes, chiming in about what's happening on screen, deliberately doing silly things just to show everyone… I've wanted to do that for ages.
Actually, in UNDERTALE, I wanted to add an arcade to Hotland. You could play games with Monster Kid, and while the player was gaming, Monster Kid would comment on all sorts of things… If the scene in THE LEGEND OF TENNA makes you feel like you're really playing with friends, I'd be thrilled.") — Toby Fox, Nintendo DREAM Vol. 376 (September 2025 issue), page 41.