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

Only extreme gamers can beet this epic skeleton. doot doot am I right gamers

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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

The attachs that give me problems are the eye shots and the finger guns

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3 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

Why is she at number 7 I have beat all these bosses but she has to be the 2nd hardest

... I'm scared of the fight I've seen videos

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4 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!

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


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


Here’s how long it took me to beat every boss after papyrus (excluding genocide bosses)

undyne: 2 days
muffet: 3 days
mtt ex: ~1 week
asgore: a couple months
photoshop flowey: 20 minutes

notice anything interesting? (hint: the point i’m trying to make is that flowey’s difficulty is overrated and asgore’s is underrated)

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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.

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.

Watch out for his dual weilding assault rifles attack. Each bullet can kill you in one shot, even with max health with max LV. Had to get my russian hacker comrade to hack the game to help me beat him.

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The Newcomers

? Mad Mew Mew

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.
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

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 Seven Human Souls

Give me a gun. - BrokenLightbulb

17 Alphys NEO

She's not even in Undertale! - BrokenLightbulb

18 Mettaton NEO Mettaton NEO

SO EASY - coolgamert

THEN WHY IS HE HERE? - 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 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

21 Lemon Bread

Very nasty first time.

Took me a few tries to beat this one

22 Knight Knight

Stupid annoying

Gives you hell

23 Greater Dog Greater Dog
24 Jerry

HE DOESN'T EVEN ATTACK. - BrokenLightbulb

25 Whimsun

This guy should be last. - BrokenLightbulb



27 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.

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