Undertale Crossovers
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BK Kirbytale by BrandonK7200 reviews
Just my take on a Kirby Undertale AU. I've been thinking about this for a while and have most of it planned out, so chapters will probably come out on a daily basis unless I'm way too busy or I'm not motivated. Feel free to let me know if my writing looks weird or characters don't act right, and I'll probably fix it. Updates on hold because I'm not motivated & I'm busy w/ stuff rn.
Crossover - Kirby & Undertale - Rated: K+ - English - Adventure/Friendship - Chapters: 3 - Words: 2,879 - Reviews: 1 - Favs: 2 - Follows: 2 - Published: 4/9 - Magolor
The Storm of Eyes by TheOriginalWriterGuy reviews
/\A Two Kinds x Undertale Crossover/\ On the journey to the Basitin Isles, Trace's voyage is intercepted by a mysterious storm, which was not predicted by Captain Eric's navigator. Hesistant to stray too far off-course, they decide to brave the storm- only to find themselves seeing into another universe. There, they traverse into a world entirely hostile to them...
Crossover - Two Kinds & Undertale - Rated: T - English - Mystery/Adventure - Chapters: 24 - Words: 37,337 - Reviews: 24 - Favs: 9 - Follows: 9 - Updated: 4/9 - Published: 4/15/2021
The Dresden Files: Beneath Mt Ebott by jgjemmett reviews
The Monsters of Mt. Ebott were trapped underground at the end of a war in millennia past, and now that they've been freed, they're walking into another one. Amidst Monster abductions, time travel and a 12 year old in the United Nations, Harry Dresden's expertise as a Wizard is required to help educate them on the workings of the modern magical world. (Dead Beat/Post Barrier)
Crossover - Dresden Files & Undertale - Rated: T - English - Mystery/Humor - Chapters: 27 - Words: 128,271 - Reviews: 125 - Favs: 188 - Follows: 217 - Updated: 4/9 - Published: 5/30/2016 - H. Dresden, Mouse, Thomas R., Asgore D.
Holdertale by Holdertale reviews
An interdimensionally lost Touta Konoe jumps down a hole to find something, anything, that might take him home. But instead of an ancient artifact or magical gateway, he finds an adventure, and new friends. Spoilers for up to Chapter 120ish of UQ Holder! and for all of Undertale.
Crossover - UQ Holder! & Undertale - Rated: T - English - Humor/Friendship - Chapters: 40 - Words: 61,162 - Reviews: 53 - Favs: 35 - Follows: 39 - Updated: 4/6 - Published: 8/7/2016 - Touta K., Asriel, Chara, Flowey
Another World - Perm Hiatus by LaeIsGone reviews
Sans has been killed by Chara once again, except this time when he wakes up he's no longer in the underground. He's in a new world that seems entirely different. A world full of people he has never seen before. What adventure awaits him? What will happen as he travels? And will he make it out alive?
Crossover - RWBY & Undertale - Rated: T - English - Adventure/Suspense - Chapters: 10 - Words: 13,544 - Reviews: 48 - Favs: 79 - Follows: 106 - Updated: 4/6 - Published: 1/16/2019 - Ruby R., Ozpin, Glynda G., Sans - Complete
Tales of a New Headspace by FunbariVoid reviews
As Sunny says goodbye to Faraway Town, he and his mother move onto Ebott City to start a new life, hoping they can leave behind everything and finally have a happy life. But that's what they thought. Sunny, along with his mother, discovers their new home is a place where humans and monsters co-exist with each other.
Crossover - Undertale & OMORI - Rated: K+ - English - Supernatural/Horror - Chapters: 3 - Words: 2,575 - Reviews: 2 - Favs: 7 - Follows: 9 - Published: 4/3 - Papyrus, Sans
Harry Potter and the Muggles Who Needed Magic by TheZorker reviews
It's been over two years since Frisk fell to the Underground, and was adopted by the Dreemurr family. One of her former foster parents has finally noticed, and come looking for her. Now, if Frisk can't find a way to bring her families together... it might just tear her apart. Book Three of The Underground's Saviour
Crossover - Harry Potter & Undertale - Rated: K+ - English - Adventure - Chapters: 20 - Words: 64,992 - Reviews: 192 - Favs: 276 - Follows: 335 - Updated: 3/27 - Published: 9/15/2018
YellowTale by YellowCaballeroFan reviews
Ever since Toby Fox made the RPG game know as Undertale 5 years ago, many people made their own versions of it, known as AUs, or Alternate Universes. Here is my AU, which stars a most likely forgotten character from the Pokemon Adventures Manga: Yellow. This is also kind of takes place after a whole bunch of stories that expand on Yellow's character. Hope you enjoy!
Crossover - Pokémon & Undertale - Rated: T - English - Adventure/Friendship - Chapters: 30 - Words: 21,530 - Reviews: 4 - Favs: 10 - Follows: 10 - Updated: 3/24 - Published: 11/9/2020 - Yellow, Pikachu
Under the Mountain by MeckaMecka reviews
One day, the barrier to the outside world sealed them in. An entire civilization living beneath a mountain, cut from the outside world. You are born in the Underground, and then you die in the Underground. (Wait, what game was this supposed to be again?)
Crossover - Fallout & Undertale - Rated: T - English - Adventure - Chapters: 9 - Words: 51,427 - Reviews: 18 - Favs: 27 - Follows: 47 - Updated: 3/19 - Published: 6/30/2018 - Lone Wanderer, Dogmeat, Frisk
Undertale: Mars Edition by SadSeals reviews
Fallen into the Underground. A place filled with monsters. A young child has to embark on a dangerous journey getting back to the surface. Luckily they don't have to travel it alone. They meet a very strange, strong (and grumpy) friend who will stand by their side against any threat. Apparently this friend is also a, "plumber"?(Cover image by me.)
Crossover - Ben 10 & Undertale - Rated: M - English - Adventure/Friendship - Chapters: 4 - Words: 10,749 - Reviews: 1 - Favs: 4 - Follows: 5 - Updated: 3/10 - Published: 8/1/2021 - OC, Frisk, Sans, Chara
LOUDERTALE but my version by Loudcrowd111 reviews
Lincoln discovers a legend about a mysterious mountain, he tried to prove to his sisters than the legend is true, but lincoln ends up falling into the underground, will Lincoln ever return?
Crossover - Loud House & Undertale - Rated: T - English - Adventure/Hurt/Comfort - Chapters: 32 - Words: 120,882 - Reviews: 32 - Favs: 39 - Follows: 36 - Updated: 3/8 - Published: 9/4/2021 - Lincoln L. - Complete
Harry Potter-Ex and the Goblet of Fire by CreativeCollective reviews
Harry Ex, adopted son of Mettaton and Papyrus, was happy. He loved his life since being taken from his abusive family. However, when he disappeared from the stage of one of his shows and appeared in the great hall at Hogwarts, he wasn't that surprised. Now he's got to do some dumb tournament? Fine. Harry has D.I.D No bashing of Weasleys or Hermione Includes UT AU's and ships
Crossover - Harry Potter & Undertale - Rated: K - English - Drama/Adventure - Chapters: 7 - Words: 10,961 - Reviews: 19 - Favs: 122 - Follows: 133 - Updated: 3/1 - Published: 10/12/2019 - Harry P., Papyrus, Mettaton Ex
Hogwarts Determination: The Chamber of Secrets by sparrow0sborne reviews
Frisk Dreemur is entering her second year when all of a sudden, fellow muggle borns are being petrified, and blood messages start appearing on the wall. As muggle born Slytherin, Frisk doesn't know if she is safe or not...
Crossover - Undertale & Harry Potter - Rated: K+ - English - Fantasy/Friendship - Chapters: 5 - Words: 17,624 - Reviews: 1 - Favs: 7 - Follows: 6 - Updated: 2/28 - Published: 2/23
Winnie the Pooh's Undertale Adventure by TurboTasticKingCandy reviews
Pooh and his friends begin a whole new adventure, way down in the Underground... (Note: Story will take a Pacifist Route)
Crossover - Winnie the Pooh & Undertale - Rated: T - English - Adventure/Friendship - Chapters: 5 - Words: 10,795 - Reviews: 10 - Favs: 8 - Follows: 10 - Updated: 2/26 - Published: 4/27/2016 - Pooh, Frisk, Flowey
Hogwarts Determination: The Sorcerer's Stone by sparrow0sborne reviews
Frisk, Chara and Asriel were your typical human and monster children raised by monsters. Until they recieve a letter letting them know they have been accepted in Hogwarts School of Witchcraft and Wizardry!
Crossover - Undertale & Harry Potter - Rated: K+ - English - Fantasy/Friendship - Chapters: 15 - Words: 39,461 - Reviews: 1 - Favs: 10 - Follows: 9 - Updated: 2/23 - Published: 2/15 - Complete
Shattered and Broken, I Will Never Leave by MistraltheSkelegirl reviews
Dr. W. D. Gaster has been in the Void for years, and has come to terms to the fact that he can't be seen or heard by anyone. But when one broken child can see him, he stays with them, and becomes the one to heal their broken Soul. FemHarry, Fatherly!Gaster, Manip!Dumbles. Please Review!
Crossover - Harry Potter & Undertale - Rated: T - English - Family - Chapters: 2 - Words: 780 - Reviews: 19 - Favs: 112 - Follows: 136 - Updated: 2/15 - Published: 2/10/2020 - Harry P., Hedwig, Gaster
Dream Potter? Wait, WHAT! by MistraltheSkelegirl reviews
Dream and Nightmare weren't actually related, though no one else knew that but them. So what happens when Dream's original world brings her back? Will they be ready to deal with her and all the crazy that decided to follow? Fem!Dream, Fem!Harry, BigBrother!Nightmare, and Multiships, including Cream and Insomnia. Now cross-posted on Wattpad.
Crossover - Harry Potter & Undertale - Rated: T - English - Adventure/Family - Chapters: 10 - Words: 12,539 - Reviews: 74 - Favs: 226 - Follows: 236 - Updated: 2/15 - Published: 1/11/2020 - Harry P., Albus D., Luna L., Sans
Genietale by Dream Dragoness reviews
Centuries ago, the people of Ebbot Island fought a terrible war with monsters, sealing them under Mount Ebbot and earning the ire of Sequin Land. Frisk, a young half-genie, received visions about the war and a feeling telling her to go to the mountain, only for her to fall into the monster kingdom. Now, Frisk must travel the Underground, harness her magic, and find a way home.
Crossover - Shantae & Undertale - Rated: T - English - Adventure/Fantasy - Chapters: 3 - Words: 14,541 - Reviews: 5 - Favs: 6 - Follows: 4 - Updated: 2/8 - Published: 5/9/2021 - OC, Shantae, Frisk, Flowey
Deathbattle! Undertale vs Xenoblade Chronicles! by CrumpsCrumbs
Soul vs Heart! Magic vs Ether! Monsters vs Homs! It's time for a collection of Deathbattles between Undertale and Xenoblade Chronicles!
Crossover - Xenoblade Chronicles & Undertale - Rated: K+ - English - Friendship - Chapters: 6 - Words: 13,522 - Favs: 1 - Updated: 2/4 - Published: 1/28 - [Reyn, Papyrus] [Shulk, Sans] - Complete
Nostalgia Critic Eats Asriel by callofdutyFTWnintendoFTL reviews
The Nostalgia Critic is hungry and really wants to devour something, or someone, who will fill his stomach full.
Crossover - Jimmy Neutron & Undertale - Rated: M - English - Friendship/Suspense - Chapters: 1 - Words: 441 - Reviews: 2 - Favs: 1 - Published: 1/26 - Principal Willoughby, Asriel - Complete
The Void Altar by Ghosttheknight
In the deepnest Ghost and Den found a void altar unlike The Shade Lord Void this one is white, they jump into and found Ink and Erorr fight...
Crossover - Undertale & Hollow Knight - Rated: T - English - Fantasy/Parody - Chapters: 1 - Words: 1,471 - Favs: 3 - Follows: 3 - Published: 1/25 - Sans, Nosk, the Knight
Journey of SOUL's by Dasansi reviews
When Harry is whisked away into UNDERTALE's dimension, what happens when he meets Frisk. What happens when Frisk looks to him for guidance. Will he change the underground for better or worse? Xover Harry Potter and Undertale.
Crossover - Harry Potter & Undertale - Rated: T - English - Hurt/Comfort/Adventure - Chapters: 8 - Words: 14,058 - Reviews: 16 - Favs: 35 - Follows: 42 - Updated: 1/20 - Published: 12/7/2021 - Harry P., Frisk, Sans, Flowey
Multiversal Christmas by Professor Orio
Temporary file, to be deleted soon
Crossover - Steven Universe & Undertale - Rated: T - English - Humor - Chapters: 1 - Words: 11,544 - Favs: 2 - Published: 1/18 - Complete
Determined Magic by the Neutrals reviews
What happens when a child that has never known a true family finally discovered one in the most unlikely of places what lengths will he go to save them? The future is unclear but one thing is certain he is filled with determination. Monster Frisk. Harry Potter is Frisk.
Crossover - Harry Potter & Undertale - Rated: M - English - Family/Hurt/Comfort - Chapters: 6 - Words: 25,331 - Reviews: 13 - Favs: 44 - Follows: 45 - Updated: 1/14 - Published: 11/16/2021 - Harry P., Asriel, Toriel, Asgore D.
Willoughby Madness! by callofdutyFTWnintendoFTL
Join this fanfic through an epic journey, the adventures of the wacky Principal Willoughby, on his quests to get what he wants!
Crossover - Jimmy Neutron & Undertale - Rated: M - English - Adventure/Sci-Fi - Chapters: 1 - Words: 2,328 - Published: 1/12 - Principal Willoughby, Asriel, Papyrus, Sans - Complete
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