What is the hardest boss of Undertale

[The Acrid]

Undertale is hands down, a pretty easy game, but there are some crazy bullet hellish bosses that are a rock to get out of your way. What do you think is the hardest boss? I say Undyne. I only died 3 times on sans, and spent over 3 hours kicking Undyne in the face. Sans had a bad time.
If you are feeling extra... bored type a list of your favorite undertale bosses, moments and quotes.

[The Acrid]

Sans' only 'difficult' attack is his slam attack, more so only his third phase of it.

[The Acrid]

After all he is the weakest enemy in the game. eh?

[MasterOfPangolins]

Sans is the hardest boss in my opinion.

[The Acrid]

I respect that.

[The Acrid]

Okay, off topic who says the fanon of this game is way overboard? I know a few fanbases are good but I'm looking at the big picture here.

[The Acrid]

When I got dunked...

Well, thank God, I deserved it.

[ₘᵣ.Dₐᵣₖₙᵢgₕₜ]

I will say Sans...he gave me a bad time....
(and also Undyne the undying it was really hard! but Sans is the hardest boss in Undertale for me)

[Ｇｉｇｓｕｋｉ浪人]

I wonder how many fangirls will say sans...

[The Acrid]

A lot, he is easy though.

[The Acrid]

I beat him and ate 2 items, legendary heros, and I had 26 hp left after he slammed me.

[Melody]

Torriel. Now don't yell at me, I know what your gonna say "What are you talking about" "She is literally one of the easiest bosses to face, in fact, she doesn't even kill you !"
Well, have you ever looked at it this way?

When you face Flowey, your completely useless fighting him, he surrounds you in "friendlyness pellets" and then you expected to die until Torriel one -shots Flowey. Secondly, in the true pacifist, Torriel stops Asgore easily with one fire attack, and it takes us several attacks to even come close to beating the king. So, if you really think about it, Torriel, is the strongest character.

[The Acrid]

Well, what about flowey, he can make an inescapable box of death, that can get you down to 1 HP and teleports you back in 'circle of everything but life'

[The Acrid]

Also, Toriel and Asgoore are statistically the same.

[The Acrid]

I will respect and consider that idea but also, consider mine. I do not mean to be impolite, as if you are, I'm sorry.

[medjed]

SAANNESSSS