Top Ten Hardest Undertale Bosses


The Top Ten

1 Sans Sans Sans or Sans the Skeleton is a character in the 2015 RPG Undertale created by Toby Fox. He is a lazy, pun-loving skeleton who is a supporting protagonist in the "pacifist" and "neutral" routes of Undertale, and a heroic antagonist/final boss of the "genocide" route. He is known for his incredibly difficult more.

Look at his attacks! Unless you are a extreme boss, this boss is the hardest times about ten!

I think Sans overrated character bus his fight hardest fight in this game but not best fight.

Lol whoever wrote ode to sans is hilarious

I died at the last spinning gaster blaster part 13 times! the rest of his special was fine but all the other attacks are annoying as hell! number 1 all the way

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2 Omega Flowey

Looks like the hardest boss ever (tied with sans) because it's so powerful imagine a talking attracting deadly flies swinging cactus hands and shooting barrages of seeds all at once. Well good luck on that one because its pretty damn hard

I died like 15 times on this fight. The main things that got me are the finger guns and the FLIES UNAVOIDABLE anyway this boss proves that Flowey is the best character and nothing will ever beat him

Dear lord this is a true nightmare hands down the scariest thing or event in undertale he is also my favorite boss because it sticks out

This ain't that hard, after the first pause, its easy as only it's first attacks are powerful, his later ones take off only 0.5% of your health...

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3 Asriel Dreemurr Asriel Dreemurr Asriel Dreemurr is a character from the 2015 game "Undertale". He was created by Toby Fox. more.

How is this fight hard? You can't even die in it!

You can die but in asriel's first attack if you die you go 2 attacks back so for asriel's first form you have to live. In his true form, however, id you die it doesn't matter.

What? This is not even that hard. Omega Flowey is WAY harder.


4 Undyne The Undying

I still think Sans is harder, but Undyne should be second place, the best part, you 100% deserve the absolute ass whooping you receive when fighting her.

Probably 2nd hardest honestly

I beat every boss in undertale within 4 or 5 tries. This is all except for undyne the undying (who I have been stuck on for weeks) and sans (who I haven't fought because I'm stuck on undyne the undying). Omega flowey took me about 3 tries, and was a really quick boss fight because I'm pretty sure you don't have to repeat phases. Asriel shouldn't be on this list because you can't die to him. Asgore was the hardest boss in all of the neutral/pacifist route (took me 5 tries), however he does not even compare to the difficulty of undyne the undying. She should be second on this list.

Should be 2nd to be honest

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5 Asgore Asgore Asgore Dreemurr is a boss monster and the king of the monsters in the 2015 RPG Undertale made by Toby Fox. Asgore is the portrayed main antagonist who plans to acquire seven human souls and use their power to break the barrier that seals the monsters underground . Aspects of his character are hinted more.

Actually, the fight is not that hard of you eat the pie.

Hard like an algebra test


I beat Asgore first try, Muffet and Undyne were pretty hard though

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6 Mettaton Mettaton Mettaton is a character in the popular 2015 RPG game, Undertale. He is a robot with a soul built by Dr. Alphys, and is the sole television star of the underground. Mettaton is a popular character in the fanbase. His notable features include his legs, and his catchphrase "OH YESSSS!"

The background music is good but he is challenging as hell!

Spam Boast and I'm not kidding it's easy after that.


7 Undyne Undyne Undyne is a main character in Toby Fox's 2016 RPG, Undertale. She is the heroic fishlike captain of the Royal Guard, who takes it upon herself to protect the monsters of the Underground. Her name is derived from the word "Undine", and is a pun on the word "Undying". Her most loved monsters are her mentor, more.

This is way harder than any of the above apart from sans.

Here's a little fun fact: I died to Undyne more than I did to Photoshop Flowey, Asriel Dreemur and Asgore combined. The NORMAL Undyne, not Undyne the Undying. WHY ME - Mewtwo660

I don’t understand how some people get through this so easily.

8 Muffet Muffet Muffet is a character from the game Undertale. She appears in a region called Hotland, selling pastries to raise money to rent a heated limo to help the spider clan from the Ruins (who are also raising a bake sale) reunite with the one in Hotland because the spiders can't cross Snowdin.

Took 3 days. I asked my dad to try. He beat it first try. What the heck?

Still stuck here

This boss was so hard to beat for me. Sure not as hard as undyne the undying and sans but this is harder than papyrus and undyne and mettaton EX!

Really really hard >:(

9 Papyrus Papyrus Papyrus is a character from the 2015 game Undertale, made by Toby Fox . He is the Younger brother of Sans the skeleton, royal guard in training, and a sentry in the town of Snowdin . Opposite to his brother, papyrus is active, loud, and full of himself; but in an endearing way. Papyrus means to become more.

He was only threatening in Disbelief. In regular Undertale, he is a cake walk. - TopTenX

I don't think you can actually die against him - it's impossible.

What the hell so easy beat him first try

10 Ruins Dummy

After I completed my Genocide route, I was feeling like I could defeat anything. And then I remembered the Dummy in the Ruins. GOD, I had to hack the game to get past him. All monsters bow before the dummy.

This is the hardest boss no doubt. The rock in the ruins might be tougher to beat though.

I find it ironic that Ruins Dummy is on the list but Mad Dummy isn't.

2 good 4 u

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The Contenders

11 Toriel Toriel Toriel is a main character in Toby Fox's 2016 RPG, Undertale. She is an amazing blend of goat and mother.

But toriel's attacks avoid you

12 Froggit

Hardcore, I was stuck on them for a very long time. He wouldn't turn yellow, and I was so confused

Please tell me you are joking. - BrokenLightbulb


13 Mad Dummy

On him rn and it is so frustrating

I don't need friends! I've got knives!

i'm out of knives.

14 Annoying Dog Annoying Dog

Hardest boss ever! Who else agrees?

15 Ultra Sans

He is awesome and he is so hard if you think sans is hard try this dude

He kills you if you don’t have the artifact

16 Alphys NEO

She's not even in Undertale! - BrokenLightbulb

Harder than any boss combine

17 Mettaton NEO Mettaton NEO

SO EASY - coolgamert

THEN WHY IS HE HERE? - BrokenLightbulb

18 Seven Human Souls

Give me a gun. - BrokenLightbulb

19 Temmie Temmie Temmie is minor character from the 2015 game Undertale made by Toby Fox. Made in the likeness of her artist, Temmie Chang, in appearance and character. Both a character and a species of monster, temmies are defined by their mix of cat and dog features, as well as their broken English. Their hidden village more.

TEMMIE for the win

So hard. - PolishDude

HOI AnD WeLcOmEz To... LiTeRaL hElL! - WarriorCatsHater

HoI I'm TeM wELcomE To TEm shOP

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20 So Sorry

Harder than undyne, muffet and maybe mettaton

21 Napstablook Napstablook Napstablook is a secondary character from Toby Fox's 2016 RPG, Undertale. He is the cousin of Mettaton, who left him in order to become famous. Due to this, poor Blooky has crippling depression.

Can't kill a ghost

Don't cheer his dapperblook...I DARE YOU

22 Lemon Bread

Very nasty first time.

Took me a few tries to beat this one

23 Jerry

I like how ditching Jerry is an option. Just ditch him a couple of times


HE DOESN'T EVEN ATTACK. - BrokenLightbulb



25 Knight Knight

Stupid annoying

Gives you hell

26 Greater Dog Greater Dog
27 Mad Mew Mew
28 Royal Guards
29 Shyren
30 Whimsun

This guy should be last. - BrokenLightbulb

31 Chara Chara Chara is a character in the game Undertale by Toby "Radiation" Fox who is one of the seven people to fall to the Underground prior to the fall of the player character. Her name can be changed by the player and will be assumed as the player character, until the Pacifist Route when Asriel asks for the more.

Oh jeez this has to be the hardest. Most people don't know how to battle Chara. Look it up on Youtube and watch. Most are fake actually or fan-made. Trust me, harder than Sans.

32 Aaron
33 Astigmatism
34 Doggo
35 Dogamy and Dogaressa
36 Endogeny Endogeny
37 Final Froggit
38 Glyde
39 Lesser Dog Lesser Dog Lesser Dog is a character from Undertale. He is part of the Snowdin Canine Unit, and is famous for his long neck.
40 Memoryhead Memoryhead
41 Moldsmal
42 Pyrope
43 Reaper Bird Reaper Bird
44 Goku Goku Son Goku (Kakarrot) is the main protagonist in Dragon Ball franchise created by Akira Toriyama in 1984. He has many abilities like, super strength, utilization of ki, flight, teleportation, super speed, enhanced reflexes, and Super Saiyan transformation that increase strength, speed, and durability. more.

I'm do so awesome

45 Flower Flower Flowey is a flower in the RPG Undertale. He is the first character you meet, and also your best friend.

This dude sssoo easy

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List Stats

600 votes
45 listings
2 years, 184 days old

Top Remixes (4)

1. Sans
2. Undyne The Undying
3. Omega Flowey
1. Sans
2. Undyne
3. Omega Flowey
1. Sans
2. Omega Flowey
3. Asriel Dreemurr

View All 4

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