Top Ten Hardest Undertale Bosses

The Top Ten
1 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.

It took me over a 100 times just to beat a lazy-funny skeleton who Actually can kill you without even fighting it's just insane oh yea now your jumping over bones which he does it pretty fast oh, great now blue then white bones its just crazy when your done halfway it just gets crazier your being thrown with force very fight with bones appearing in the red box which is very hard if u lose control, and u have to dodge all the gaster blasters SOMEHOW and then the final attack going threw a wave of bones then ALL THE FREAKING BLASTERS U HAVE TO RUN AWAY FROM THEN HE THROWS YOU EVERYWHERE until when u kill him... it's also the 1. saddest death. he says "Papyrus do u want anything" and u feel really bad now. :'(

I've died probably over 100 times at the point and I'm not getting anywhere close to beating him. My personal ranking is: #1 (by far) Sans, #2 Undyne the Undying (probably died over 15 times), #3 Omega Flowey beat him in one attempt on my first playthrough and only died once on my second.

I couldn't get past the final gaster blaster circle for SO long. Weeks after my first attempt on computer (and maybe 57th) I downloaded it on my switch, and the controls are so much better. The third bone stab (where he flings you into a random wall in the box and bones try to stab you) was almost impossible to get past undamaged. And I hated constantly being hit by those final gaster blasters. His fight was by far the hardest in the game. This makes undyne the undying look like a pushover. So yeah... I ended up having a VERY bad time.

I think Sans is pretty easily the hardest because of many reasons such as, his attacks at the start are unexpected and will add a quick few deaths to the amount you will have through this fight, players will get annoyed eventually and when people are annoyed they play worse, Sans irritates the player by dodging their knife swings, Sans final attack is very hard to dodge, all of Sans attacks involve parkour dodging and swift movements and also within sans fight you spend a lot of the fight with the blue heart which is harder then the red heart. Those are my reasons why sans fight is the hardest and by the way I’m sorry this comment is very long I just wanted to point out a lot of reasons thank you for reading!

2 Omega Flowey

Other boses are challenging but you can memorize there attack patterns over many repeats you can do that with flowey sure but I don't have the reflexes. I remember coming out of the asgore fight and found him one of the easiest bosses but then flowey came and killed me almost instantly over and over I haven't fought sans or Asriel but I can't see them coming close to the difficulty of flow since I can't fight him for more then 20 seconds

Although his battle does SAVE, no amount of skill can let you NOT DIE on this guy. To be fair, I haven't attempted the genocide route, so I haven't battled Undyne the Undying or Sans, but he is much harder than Asriel, as his battle SAVES even more.

I say omega/photoshop flowey is the hardest... He throws all his attacks at once! But... Asriel posseses flowey then... How does he have 2 forms?!?!
Wait... Actually 3
But still!

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

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

Sans may be the strongest but he can't even beat asgore nor asriel since sans is the almost main character dosen't mean he's the strongest

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.

But guys, try beating Asriel without even supposedly dying, you'll see he is DAMN HARD

Didn't want to vote for this, but you cannot die during this fight. Froggit is easier

4 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.

Asgore took me a while to beat but after that, I got his attacks in my head easier.

The only boss that I died to more than 1 time (Not counting Papyrus)

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

Asgore is like an exam you didn't study for.

5 Undyne The Undying 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.

Undertale is a flawless game besides the fact that Toby wanted the 2 bosses of the genocide run to be hard and not so fun. But I think that some parts of the undyne fight are pretty fun pretty good boss. But why is she at 5, she should be at least 2 maybe even 1

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.

Out of all the bosses I've fought so far, Undyne The Undying takes my vote. Bear in mind that since I haven't been able to get past her yet, I haven't fought Sans or any bosses that only appear in Genocide past Undyne The Undying, but she is easily the hardest so far.

While Sans is a battle of patterns, Undyne The Undying isn't it is a battle that puts your abilities of playing videogames on trial, certainly the hardest bossfight.
The speedchanging attacks based on the music really are impressive, and the music is phenomenal, it gives you motivation to win.

6 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!"

Mettaton is the hardest pacifist fight, in my opinion. His attacks are super chaotic, and almost impossible to dodge. Some may say Asgore is harder, but once you get his attacks he's super easy. It took me 8 items to beat Mettaton and only 5 for Asgore. I died 3 times for both but barely beat Mettaton with 2 health whereas beat Asgore handily. The reason why Mettaton is harder than Flowey or Asriel is because you can't lose to them. Anyway, Mettaton is epic.

Only person I died to in pacifist run through (and that was my first time through)

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 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.

The only way to spare her is running away until your red and then run to the hotland bridge, let her faint, then give her water.

Undyne is just hard no matter if its genocide undyne or regular

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

Not too hard after I killed her once in a neutral run it was pretty easy to kill her again, good thing you didn’t put undyne the undying because that’d be a whole other story, it’d be writing an essay on that

By Derpo

8 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.

Muffet got my vote. The way her attacks come at you. Eat a spider donut in front of her to skip the battle or if you already bought a spider donut in the ruins, in the dinner phase a spider will bring up a note and the battle will end. Struggle or pay to slow her attacks. Took me many tries.

Muffet is actually pretty easy to beat IF you saved the spider donut or spider cider. I had it and ate it in front of her. But if you don't have one, you have to spare her 17 times, I think.

Muffet is my fave character and super evil and cute. I mean, she can also control your soul like Sans and every time I see the doughnuts and pastries I get hungrier which breaks my concentration

Its just so annoying how the pet is impossible to escape from! It took me like 15 tries to beat her... on my genocide run!

9 Ruins Dummy

Everything was a piece of cake until this fight. Took me SO LONG to get past it. Also, beware it's last attack. Those bullets are insta-kills!
What the heck, Toby!
And this site! How is this number 6?! It's worse than Sans!

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.

Why is sans the fkrst? The dummy is a lot harder. Unless of course you're carefull not to activate him. If you do be careful for hsi God attack. And don't call for help, you'll get Toriel killed.

I tried so many times to get past it, but it was too hard. Eventually, I had to hack my game. What was Toby thinking? Putting a battle like that in the game?

10 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.

No...Papyrus is easy...Plus you can skip his battle and befriend him if you die three times instead..

Papyrus is pretty easy if you ask him on a date then he gets really distracted

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

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

You can because I'm bad at the game, I did the route where I skip his fight.

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

Technically, you can't die in this fight, but just TRY to not get to 2 HP when you are on pacifist. It's freaking impossible!

Strangely I defeated Photoshop Flowey in three tries but on Tori on my second playthrough this was hard.

But toriel's attacks avoid you

how. do. you. not. die. 10. times.

12 Mad Dummy

He took me around 4 or 5 tries to beat, so not really that hard...

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

I'm out of knives.

Really frustrated me on my first playthrough.

On him rn and it is so frustrating

13 Disbelief Papyrus

Bones orange bones blue bones orange Gaster blasts sans and Undyne the undying

He is way stronger than regular papyrus

*Papyrus no longer believes in you

This is just a fan made battle.

14 Froggit

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

Froggit didn't understand what you said, but was flattered anyways.

Hardest boss in game. don't even tell me anything else you fool!

Just a normal froggit, but it took me 26 trys and this froggit, is a hacker, or am I gliched?


I mean... I like his lore.

He made the op sans

The blasts lol

its gaster, he can't die

16 Annoying Dog

This is actually mist likely the strongest character in the game, he created this world (undertake), so he can easily destroy it all, he could kill you (Frisk),Sans, Papyrus, Undyne, just with a single button

By Derpo

Hardest boss ever! Who else agrees?

Is it even a boss


17 Ultra Sans

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

The strongest sans

Lasers hands and laser moever

He kills you if you don’t have the artifact

18 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.

Legitimately can't get rid of her in your files (unless you do some complex "hacking" stuff) so yeah

Chara is a god. She can kill you so quick.

At the end, you end up dying from her

19 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.

Da tems to hard to beats

Temmie for the win

HOi wElCOme tO...


HOI AnD WeLcOmEz To... LiTeRaL hElL!

20 Frisk

You control Frisk, so you can't kill her. Maybe in fan-games, but not Undertale.

Frisk is easy to beat. Just get her soul to run into something harmful.

Frisk is easily the hardest boss in the entire game, you can’t even hit them. Why did Toby Fox put an unbeatable boss in the game smh

I just didn’t know why I beat the game without dying once,even if I run Frisk’s soul into the attacks.
She is the best character.

21 Alphys NEO

The attacks cool but difficult

Alphys have lasers Gaster blasts fast forward play raced rewind and
light nig

Harder than any boss combine

She's not even in Undertale!

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

He almost instakills you with a single hit, manipulates you and makes it impossible to escape. By sheer luck they make a mistake and use a super heal on you which they could use on themselves easily! Also don't even have the option to act! They just have one attack and they go first instead of you plus they will remember everything!

Yeah also the omega flowey is insaneley hard

This dude sssoo easy

Hell to the naaw

23 So Sorry

I feel so sorry for so sorry. He doesn't mean to fight you. He just ran into you and started the fight

This is a secret boss, but it's hard, I can say it's the sixth hardest boss after ASGORE

Harder then muffet, undyne, papyrus and maybe asgore but not mettaton

Harder than undyne, muffet and maybe mettaton

24 Dusttale Sans

He has fReAkInG more Determination than you in the fan-game.

Seen videos and don't even wanna try cause of how he is

;-; I don't know why did I vote for him

This dood is hecking insane, like bro.

25 Greater Dog

This is easy all of the attacks just barking when you just used ACT (in pacifist run) I don't know what happens if we do a GENOCIDE RUN. maybe you should try it!.

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